diff --git a/src/advanced.js b/src/advanced.js
index 72434e1..474f260 100644
--- a/src/advanced.js
+++ b/src/advanced.js
@@ -5,32 +5,32 @@ const numsToMerge = [...nums]
 const arrayToExtend = [...nums]
 
 // 1. Set this variable to the sum of the first and last numbers in the nums array
-const firstPlusLast = 0
+const firstPlusLast = (nums[0] + nums[nums.length-1])
 
 // 2. set this variable to the index where the number 14 is located in the array
-const indexOfFourteen = 0
+const indexOfFourteen = nums.indexOf(14)
 
 // 3. remove the last 3 elements of the array in one single instruction
-const withoutLastThree = 0
-
+const withoutLastThree = nums.slice(0, nums.length -3)
 // 4. Add the number 15 before the number 8 in the array arrayToExtend
 // note: use splice, read the documentation carefully
+arrayToExtend.splice(arrayToExtend.indexOf(8), 0, 15)
 
 // 5. check if the array includes the number 100
-const includesHundred = true
+const includesHundred = nums.includes(100)
 
 // 6. extract the numbers 7, 3, 8 into a new array
-const withSevenThreeEight = []
+const withSevenThreeEight = nums.slice(nums.indexOf(7), (nums.indexOf(8) +1))
 
 // 7. add the numbers from otherNums to the end of numsToMerge
-const combinedNums = []
+const combinedNums = numsToMerge.concat(otherNums)
 
 // 8. create a new array with the cities 'Rome', 'Paris' and 'Barcelona'
-const newCities = []
+const newCities = ['Rome', 'Paris', 'Barcelona']
 
 // 9. use the spread operator ... to clone the cities array and add 'Berlin' to the end and 'Sydney' to the start
 // note: read about the spread operator
-const moreCities = []
+const moreCities = ['Sydney', ...newCities, 'Berlin']
 
 module.exports = {
   a: firstPlusLast,
diff --git a/src/core.js b/src/core.js
index 11bda56..dce4fcf 100644
--- a/src/core.js
+++ b/src/core.js
@@ -3,22 +3,22 @@ const teachers = ['Nathan', 'Ed', 'Steve', 'Phil', 'Carlo', 'Lewis', 'Shahzad']
 
 // 1. Using an index on the teachers array, change the value of the
 // fourthTeacher variable below to be the fourth teacher listed in the array
-const fourthTeacher = undefined
+const fourthTeacher = teachers[3]
 
-// 2. Replace the fifth teacher in the teachers array with 'Patrick'
 
+// 2. Replace the fifth teacher in the teachers array with 'Patrick'
+teachers[4] = 'Patrick'
 // 3. Remove the last teacher from the array and save them in lastTeacher below
-const lastTeacher = undefined
-
+const lastTeacher = teachers.pop()
 // 4. Remove the first teacher from the array and save them in firstTeacher below
-const firstTeacher = undefined
+const firstTeacher = teachers.shift()
 
 // 5. Add a teacher named 'Vanessa' to the end of the teachers array
-
+teachers.push("Vanessa")
 // 6. Remove 'Ed' from the teachers array
-
+teachers.splice(teachers.indexOf("Ed"), 1)
 // 7. Add a teacher named 'Sarah' to the beginning of the teachers array
-
+teachers.unshift("Sarah")
 // Don't change the code below this line
 module.exports = {
   teachers,
@@ -26,3 +26,4 @@ module.exports = {
   lastTeacher,
   firstTeacher
 }
+
diff --git a/src/extension.js b/src/extension.js
index 6482719..b5cff43 100644
--- a/src/extension.js
+++ b/src/extension.js
@@ -8,20 +8,19 @@ const countries = ['Bolivia', 'Jordan', 'Greenland']
 const fruits = ['Apple', 'Orange', 'Pear']
 
 // 1. Add Fred to the names array
-
+names.unshift("Fred")
 // 2. Add 4 to the end of the numbers array
-
+numbers.push(4)
 // 3. Add Rio to the start of the cities array
-
+cities.unshift("Rio")
 // 4. Remove the first colour from the colours array
-
+colours.shift()
 // 5. Remove the last item from the keys array
-
+keys.pop()
 // 6. Remove Jordan from the countries array
-
+countries.splice(countries.indexOf("Jordan"), 1)
 // 7. Remove the last fruit from the fruits array and store it in pear below
-const pear = undefined
-
+const pear = fruits.pop()
 // Do not change the code below
 module.exports = {
   a: names,