Passed all test

Boolean.CSharp.Main/Core.cs

@@ -30,7 +30,7 @@ public Car(string Make)
                 }
             */
 
-            Car car = new Car("Volkswagen");
+            Car car = new Car("Volkswagen", "hello");
             /*  When the car in instantiated, the constructor is passed a string
              in this case Volkswagen which is a Make of car is passed in.
              Within the constructor the 'string Make' variable has scope within the constructor and assiged to the _make member now visible to the whole class
@@ -92,7 +92,7 @@ public Bicycle Question3()
             //See there is somewhere to store the number of wheels the bike has 
             //but no constructor to set this
             //TODO: 3. Add a constructor to the Bicycle class that populates the _wheelCount variable
-            Bicycle bike = new Bicycle();
+            Bicycle bike = new Bicycle(2);
 
             return bike;
 
@@ -108,7 +108,7 @@ public Unicycle Question4()
 
             //TIP  see we already have an internal member for the unicyclist name:  _nameOfUnicyclist so you can use this to store the name internally
             //      it is good practice to name internal class variable with an _ at the beginning
-            Unicycle unicycle = new Unicycle();
+            Unicycle unicycle = new Unicycle("Hans");
 
 
 
@@ -132,9 +132,10 @@ What are the parameters and types?
              */
             Aeroplane plane = new Aeroplane();            
             plane.FlightDetails("LHR", "JFK");
-            
+
             //TODO:  5.  Call the FlightDetails method that sets the cancelled message and  cancel the flight
-
+
+            plane.FlightDetails("Flight canceled");
            //write code here 
 
             return plane;

Boolean.CSharp.Main/Extension.cs

@@ -7,23 +7,51 @@
 namespace Boolean.CSharp.Main
 {
     public class Extension
-    {        
+    {
 
         //Implement the following methods:
 
         //TODO: 1. add, which accepts two floats and returns a float (both floats added together)
+        public float add(float numOne, float numTwo) => numOne + numTwo;
 
         //TODO: 2. add, which accepts two doubles and returns a double (both doubles added together)
+        public double add(double numOne, double numTwo) => numOne + numTwo;
 
         //TODO: 3. subtract, which accepts two floats and returns a float (first float minus second float)      
+        public float subtract(float numOne, float numTwo) => numOne - numTwo;
 
         //TODO: 4. subtract, which accepts a String and a char and returns a string with all instances of the provided char removed        
+        public string subtract(string word, char letter)
+        {
+            return word.Replace(letter.ToString(), "");
+        }
 
         //TODO: 5. multiply, which accepts two ints and returns an int (first int multiplied by second int)
-
+        public int multiply(int numOne, int numTwo) => numOne * numTwo;
         //TODO: 6. multiply, which accepts a string and an int, and returns a string containing the provided string as many times as the provided int separated by a comma. E.g. multiply("Hello", 3) -> "Hello,Hello,Hello"
-
+        public string multiply(string word, int num)
+        {
+            string repeatedWord = "";
+            for (int i=0; i<num; i++)
+            {
+                repeatedWord += $"{word},";
+            }
+            repeatedWord = repeatedWord.TrimEnd(',');
+            return repeatedWord;
+        }
         //TODO: 7. multiply, which accepts an array of Strings that each contain a number, and an int. The method should return an array of ints that contain the value of multiplying each String number by the provided int E.g. multiply(["2", "7", "3"], 3) -> [6, 21, 9]
-
+        public int[] multiply(string[] numbers, int factor)
+        {
+            int[] multipliedList = new int[numbers.Length];
+
+            for (int i=0;i < numbers.Length; i++)
+            {
+                int mulitpliedInt = int.Parse(numbers[i]);
+                mulitpliedInt *= factor;
+
+                multipliedList[i] = mulitpliedInt;
+            }
+            return multipliedList;
+        }
     }
 }

Boolean.CSharp.Main/Misc/Bicycle.cs

@@ -10,6 +10,13 @@ public class Bicycle
     {
         private int _wheelCount;
 
+        public Bicycle(int wheelCount) { 
+            WheelCount = wheelCount;
+            _wheelCount = wheelCount;
+        }
+
         public int WheelCount { get; set; }
     }
+
+
 }

Boolean.CSharp.Main/Misc/Car.cs

@@ -23,6 +23,12 @@ public Car(string Make)
             _model = string.Empty;
         }
 
+        public Car(string Make, string Model)
+        {
+            _make = Make;
+            _model = Model;
+        }
+
         public string Make
         {
             get => _make;

Boolean.CSharp.Main/Misc/Motorbike.cs

@@ -11,7 +11,7 @@ public class Motorbike
     {
         private string _make;
         private string _model;
-        private int _cc = 0;
+        private int _cc = 373;
 
         public Motorbike()
         {

Boolean.CSharp.Main/Misc/Unicycle.cs

@@ -10,6 +10,8 @@ public class Unicycle
     {
         private string _nameOfUnicyclist;
 
+        public Unicycle(string nameOfUnicyclist) { _nameOfUnicyclist = nameOfUnicyclist; }
+
         public string NameOfUnicyclist { get => _nameOfUnicyclist; set => _nameOfUnicyclist = value; }
         public int WheelCount { get; set; } = 1;
     }

Boolean.CSharp.Test/ExtensionTests.cs

@@ -90,7 +90,7 @@ public void TestQuestion6()
             string result = extension.multiply(source, 3);
 
             Assert.IsTrue("Hello,Hello,Hello" == result);
-        }
+        }           
         [Test]
         public void TestQuestion7()
         {