diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..d5670d82b 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -4,8 +4,18 @@
   The business is breaking out into a new market and need to convert prices to USD
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
+function convertToUSD(pound) {
+  let usd = pound * 1.4;
+  return usd;
+  //  return "$" + pound * 1.4.toFixed(2);
+}
 
-function convertToUSD() {}
+// function convertToUSD(amountInPounds) {
+//   const exchangeRate = 1.4;
+//   return amountInPounds * exchangeRate;
+// } // suggested in 'solutions'
+
+// console.log(convertToUSD(200));
 
 /*
   CURRENCY CONVERSION
@@ -15,8 +25,19 @@ function convertToUSD() {}
   They have also decided that they should add a 1% fee to all foreign transactions, which means you only convert 99% of the £ to BRL.
 */
 
-function convertToBRL() {}
+function convertToBRL(pound) {
+  let brl = parseFloat(((pound / 100) * 99 * 5.7).toFixed(2));
+  return brl;
+}
+
+// function convertToBRL(amountInPounds) {
+//   const transactionFee = 0.01;
+//   const exchangeRate = 5.7;
+//   const amountAfterFee = amountInPounds * (1 - transactionFee);
+//   return amountAfterFee * exchangeRate;
+// } //suggested in 'solutions'
 
+// console.log(convertToBRL(10));
 /* ======= TESTS - DO NOT MODIFY ===== 
 There are some Tests in this file that will help you work out if your code is working.
 
diff --git a/extra/2-piping.js b/extra/2-piping.js
index b4f8c4c1b..167b569fd 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,52 @@
   the final result to the variable goodCode
 */
 
-function add() {
-
+function add(a, b) {
+  return a + b;
 }
 
-function multiply() {
+console.log(add(20, 9));
 
+function multiply(a, b) {
+  return a * b;
 }
 
-function format() {
+console.log(multiply(2, 10));
 
+function format(num) {
+  return "£" + eval(num);
 }
 
+console.log(format(45));
+
 const startingValue = 2;
+function badPractice() {
+  return badCode;
+}
+
+let badCode = "£" + (startingValue + 10) * 2;
+
+console.log(badPractice());
+
+let incrementedValue = startingValue + 10;
+let doubledValue = incrementedValue * 2;
+let formattedValue = "£" + doubledValue;
+
+function goodPractice() {
+  return goodCode;
+}
+
+let goodCode = formattedValue;
+
+// let goodCode = format(multiply(add(startingValue, 10), 2)); //suggested in 'solutions'
 
 // Why can this code be seen as bad practice? Comment your answer.
-let badCode =
+
+// Const should be used for the values we don't re-assign. The name startingValue suggests otherwise
 
 /* BETTER PRACTICE */
 
-let goodCode =
+// let goodCode =
 
 /* ======= TESTS - DO NOT MODIFY ===== 
 There are some Tests in this file that will help you work out if your code is working.
diff --git a/extra/3-magic-8-ball.js b/extra/3-magic-8-ball.js
index 46f65f928..9716db3a2 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -43,11 +43,46 @@
     Very doubtful.
 */
 
+let answers = [
+  "It is certain.",
+  "It is decidedly so.",
+  "Without a doubt.",
+  "Yes - definitely.",
+  "You may rely on it.",
+  "As I see it, yes.",
+  "Most likely.",
+  "Outlook good.",
+  "Yes.",
+  "Signs point to yes.",
+  "Reply hazy, try again.",
+  "Ask again later.",
+  "Better not tell you now.",
+  "Cannot predict now.",
+  "Concentrate and ask again.",
+  "Don't count on it.",
+  "My reply is no.",
+  "My sources say no.",
+  "Outlook not so good.",
+  "Very doubtful.",
+];
+
 // This should log "The ball has shaken!"
 // and return the answer.
+
+function displayAnswer() {
+  let index = Math.floor(Math.random() * answers.length);
+  let answer = answers[index];
+
+  return answer;
+}
+
+console.log(displayAnswer());
 function shakeBall() {
-  //Write your code in here
+  console.log("The ball has shaken!");
+  return displayAnswer();
 }
+let answer = shakeBall();
+console.log("my answer is " + answer);
 
 /* 
   This function should say whether the answer it is given is
@@ -58,9 +93,81 @@ function shakeBall() {
 
   This function should expect to be called with any value which was returned by the shakeBall function.
 */
-function checkAnswer(answer) {
+function checkAnswer(answerToCheck) {
   //Write your code in here
+
+  if (answers.indexOf(answerToCheck) < 5) {
+    return "very positive";
+  } else if (answers.indexOf(answerToCheck) < 10) {
+    return "positive";
+  } else if (answers.indexOf(answerToCheck) < 15) {
+    return "negative";
+  } else {
+    return "very negative";
+  }
 }
+console.log(checkAnswer(answer));
+
+// console.log(displayAnswer());
+
+// const veryNegativeAnswers = [
+//   "Don't count on it.",
+//   'My reply is no.',
+//   'My sources say no.',
+//   'Outlook not so good.',
+//   'Very doubtful.',
+// ];
+// const negativeAnswers = [
+//   'Reply hazy, try again.',
+//   'Ask again later.',
+//   'Better not tell you now.',
+//   'Cannot predict now.',
+//   'Concentrate and ask again.',
+// ];
+// const positiveAnswers = [
+//   'As I see it, yes.',
+//   'Most likely.',
+//   'Outlook good.',
+//   'Yes.',
+//   'Signs point to yes.',
+// ];
+// const veryPositiveAnswers = [
+//   'You may rely on it',
+//   'You may rely on it',
+//   'It is decidedly so.',
+//   'It is certain.',
+// ];
+// const possibleAnswers = veryNegativeAnswers.concat(
+//   negativeAnswers,
+//   positiveAnswers,
+//   veryPositiveAnswers
+// );
+// // This should log "The ball has shaken!"
+// // and return the answer.
+// function shakeBall() {
+//   //Write your code in here
+//   const randomIndex = Math.floor(Math.random() * possibleAnswers.length);
+//   const randomAnswer = possibleAnswers[randomIndex];
+//   const message = 'The ball has shaken!';
+//   console.log(message);
+//   return randomAnswer;
+// }
+
+// /*
+//   This function should say whether the answer it is given is
+//     - very positive
+//     - positive
+//     - negative
+//     - very negative
+//   This function should expect to be called with any value which was returned by the shakeBall function.
+// */
+// function checkAnswer(answer) {
+//   const answerIndex = possibleAnswers.indexOf(answer);
+//   if (answerIndex >= 15) return 'very positive';
+//   if (answerIndex >= 10) return 'positive';
+//   if (answerIndex >= 5) return 'negative';
+//   return 'very negative';
+// } //suggested in 'solutions'
 
 /* 
 ==================================
@@ -101,7 +208,9 @@ test("magic 8 ball returns different values each time", () => {
     );
   }
 
-  let seenPositivities = new Set(Array.from(seenAnswers.values()).map(checkAnswer));
+  let seenPositivities = new Set(
+    Array.from(seenAnswers.values()).map(checkAnswer)
+  );
   if (seenPositivities.size < 2) {
     throw Error(
       "Expected to random answers with different positivities each time shakeBall was called, but always got the same one"
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index d9e004465..9104a8327 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,18 +1,19 @@
 // There are syntax errors in this code - can you fix it to pass the tests?
 
-function addNumbers(a b c) {
+function addNumbers(a, b, c) {
   return a + b + c;
 }
 
-function introduceMe(name, age)
-  return `Hello, my {name}` is "and I am $age years old`;
+function introduceMe(name, age) { 
+  return `Hello, my name is ${name} and I am ${age} years old`;
+}
 
 function getTotal(a, b) {
-  total = a ++ b;
+  let total = a + b;
 
-  return "The total is total";
+  return "The total is " + total;
 }
-
+// //
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9eb8c8cd7..2adb4e95a 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,16 @@
 // The syntax for these functions is valid but there are some errors, find them and fix them
 
 function trimWord(word) {
-  return wordtrim();
+  return word.trim();
 }
 
 function getStringLength(word) {
-  return "word".length();
+  return word.length;
+   
 }
 
 function multiply(a, b, c) {
-  a * b * c;
-  return;
+  return a * b * c;
 }
 
 /* 
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..dc68855bb 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,18 +1,28 @@
 // Add comments to explain what this function does. You're meant to use Google!
+
+//  the output is what the function returns, which is Math.random() * 10; _ random method class Math = The Math.random() static method returns a floating-point, pseudo-random number that's greater than or equal to 0 and less than 1, then * 10 and it could be a number < 10 && >0  
+
 function getRandomNumber() {
-  return Math.random() * 10;
+  return Math.random() * 10; 
 }
-
+ 
 // Add comments to explain what this function does. You're meant to use Google!
+// The concat() method concatenates the string arguments to the calling string and returns a new string. in this case the two argument will be joined without any space in between
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
 
+
+
 function concatenate(firstWord, secondWord, thirdWord) {
+  return firstWord.concat(` ${secondWord} ${thirdWord}`);
+  
+
   // Write the body of this function to concatenate three words together.
   // Look at the test case below to understand what this function is expected to return.
 }
-
+console.log(concatenate("code" , "your", "future"));
+  
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..1fb81fd3a 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,15 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+
+function calculateSalesTax(productPrice) {
+    let salesTax = productPrice * 0.2;
+    return productPrice + salesTax
+}
+
+// let totalPrice1 = calculateSalesTax(200);
+// console.log(totalPrice1);
+ 
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +25,13 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(price) {
+    let productPriceRes = calculateSalesTax(price);
+
+    return `£${productPriceRes.toFixed(2)}`; 
+
+}
+  
 
 /* 
 ===================================================