diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..a8a2be91a 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,7 +5,10 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(Pound) {
+  return Pound * 1.4;
+
+}
 
 /*
   CURRENCY CONVERSION
@@ -15,7 +18,11 @@ 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) {
+  const priceAfterFee = 0.99;
+  const BRL = priceAfterFee * Pound * 5.7;
+  return Number(BRL.toFixed(2));
+}
 
 /* ======= 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..2afee6a42 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,30 +16,32 @@
   the final result to the variable goodCode
 */
 
-function add() {
-
+function add(a, b) {
+return a + b;
 }
 
-function multiply() {
-
+function multiply( a, b) {
+return a * b;
 }
 
-function format() {
+function format(number) {
+  return `£${number}`;
 
 }
 
 const startingValue = 2;
 
 // Why can this code be seen as bad practice? Comment your answer.
-let badCode =
+//It can be seen as a bad code beacuse everything is in one line which makes it hard to read and understand.
+const badCode = format((startingValue + 10)*2);
 
 /* BETTER PRACTICE */
 
-let goodCode =
-
-/* ======= TESTS - DO NOT MODIFY ===== 
-There are some Tests in this file that will help you work out if your code is working.
+let addition = add(startingValue, 10);
+let multipication = multiply(addition, 2);
+let goodCode = format(multipication);
 
+/*
 To run the tests for just this one file, type `npm test -- --testPathPattern 2-piping` into your terminal
 (Reminder: You must have run `npm install` one time before this will work!)
 */
diff --git a/extra/3-magic-8-ball.js b/extra/3-magic-8-ball.js
index 46f65f928..7fc3a7aa4 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -1,7 +1,7 @@
 /**
 
   Let's peer into the future using a Magic 8 Ball!
-  https://en.wikipedia.org/wiki/Magic_8-Ball 
+  i/Magic_8-https://en.wikipedia.org/wikBall 
 
   There are a few steps to being able view the future though:
   * Ask a question
@@ -13,40 +13,53 @@
   and have different levels of positivity or negativity.
 
   Below are the possible answers:
-
-  ## Very positive
-    It is certain.
-    It is decidedly so.
-    Without a doubt.
-    Yes - definitely.
-    You may rely on it.
-
-  ## Positive
-    As I see it, yes.
-    Most likely.
-    Outlook good.
-    Yes.
-    Signs point to yes.
-
-  ## Negative
-    Reply hazy, try again.
-    Ask again later.
-    Better not tell you now.
-    Cannot predict now.
-    Concentrate and ask again.
-
-  ## Very negative
-    Don't count on it.
-    My reply is no.
-    My sources say no.
-    Outlook not so good.
-    Very doubtful.
-*/
+  */
+
+  let veryPositiveAnswers = [
+  "It is certain.",
+  "It is decidedly so.",
+  "Without a doubt.",
+  "Yes - definitely.",
+  "You may rely on it.",
+];
+    
+let positiveAnswers= [
+  "As I see it, yes.",
+  "Most likely.",
+  "Outlook good.",
+  "Yes.",
+  "Signs point to yes.",
+]; 
+
+  let negativeAnswers = [
+  "Reply hazy, try again.",
+  "Ask again later.",
+  "Better not tell you now.",
+  "Cannot predict now.",
+  "Concentrate and ask again.",
+];
+    
+  let veryNegativeAnswers = [
+   "Don't count on it.",
+  "My reply is no.",
+  "My sources say no.",
+  "Outlook not so good.",
+  "Very doubtful.",
+];
+
+let allAnswers = [
+  ...veryPositiveAnswers,
+  ...positiveAnswers,
+  ...negativeAnswers,
+  ...veryNegativeAnswers,
+];
 
 // This should log "The ball has shaken!"
 // and return the answer.
 function shakeBall() {
-  //Write your code in here
+  console.log("The ball has shaken!");
+  let randomIndex = Math.floor(Math.random() * allAnswers.length);
+  return allAnswers[randomIndex];
 }
 
 /* 
@@ -59,7 +72,16 @@ function shakeBall() {
   This function should expect to be called with any value which was returned by the shakeBall function.
 */
 function checkAnswer(answer) {
-  //Write your code in here
+  if (veryPositiveAnswers.includes(answer)) {
+    return "very positive";
+  } else if (positiveAnswers.includes(answer)) {
+    return "positive";
+  } else if (negativeAnswers.includes(answer)) {
+    return "negative";
+  } else if (veryNegativeAnswers.includes(answer)) {
+    return "very negative";
+  }
+
 }
 
 /* 
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index d9e004465..294f4d671 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;
+  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..ff5b064e1 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,15 @@
 // 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..29fa0887a 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -2,15 +2,17 @@
 function getRandomNumber() {
   return Math.random() * 10;
 }
+//it returns a number between 0 and 1, excluding 1.so multiplying with it 10,returns number between 0 and 10 but not 10.
 
 // Add comments to explain what this function does. You're meant to use Google!
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
-
+//function combine2words concatinates two strings.
 function concatenate(firstWord, 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.
+  return( `${firstWord} ${secondWord} ${thirdWord}`);
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..5103e0cb7 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,10 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(sales) {
+  const tax = 0.2 * sales;
+  return tax + sales;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +20,9 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(sales) {
+  return "£" + calculateSalesTax(sales) .toFixed(2);
+}
 
 /* 
 ===================================================