diff --git a/csharp-fundamentals-strings.Main/Core.cs b/csharp-fundamentals-strings.Main/Core.cs
index 141c9a7..a08903b 100644
--- a/csharp-fundamentals-strings.Main/Core.cs
+++ b/csharp-fundamentals-strings.Main/Core.cs
@@ -14,7 +14,7 @@ public class Core
         //TODO: 1. The brokenUrl member above contains an invalid URL. There's a z instead of an s in the protocol (httpz instead of https).
         // Using the `replace` method on brokenUrl, set the fixedUrl member below to the correct value.
         // https://learn.microsoft.com/en-us/dotnet/api/system.string.replace?view=net-7.0
-        public string fixedUrl => string.Empty;
+        public string fixedUrl => brokenUrl.Replace("httpz", "https");
 
 
         // Here's a documentation link for all string methods, use it to figure out how to complete the rest of these requirements:
@@ -23,27 +23,27 @@ public class Core
 
         //TODO: 2. There are currently some upper case characters in the URL. Using an appropriate string method on the fixedUrl member above,
         // set the value of lowerCasedUrl.
-        public string lowerCasedUrl => string.Empty;
+        public string lowerCasedUrl => fixedUrl.ToLower();
 
 
         //TODO: 3. There is still white space on both ends of the URL! Use the appropriate string method to trim that white space
         // and set the value of the url member below
-        public string url => string.Empty;
+        public string url => lowerCasedUrl.Trim();
 
 
         //TODO: 4. Using the appropriate string method on url, set the value of the protocol member below
-        public string protocol => string.Empty;
+        public string protocol => url.Split(":")[0];
 
 
         //TODO: 5. Using the appropriate string method on url, set the value of the domain member below
-        public string domain => string.Empty;
+        public string domain => url.Split("/")[2];
 
 
         //TODO: 6. Set the length member below to the length of the url member
-        public int length => 0;
+        public int length => url.Length;
 
 
         //TODO: 7. Using concatenation and existing members, set the faqUrl member below to the faq page of the boolean website
-        public string faqUrl => string.Empty;
+        public string faqUrl => $"{protocol}://{domain}/faq";
     }
 }
diff --git a/csharp-fundamentals-strings.Main/Extension.cs b/csharp-fundamentals-strings.Main/Extension.cs
index ac3b7b2..2f8f97b 100644
--- a/csharp-fundamentals-strings.Main/Extension.cs
+++ b/csharp-fundamentals-strings.Main/Extension.cs
@@ -33,6 +33,7 @@ public void example()
             // 0. Print the word "Hello"
             // WRITE YOUR CODE BETWEEN THIS LINE...
             Console.WriteLine("Hello");
+
             // ...AND THIS LINE
         }
 
@@ -43,7 +44,9 @@ public StringBuilder one()
             // 1. Using the sb variable above, add "Hello, world!" to the StringBuilder
             // WRITE YOUR CODE BETWEEN THIS LINE...
 
+            sb.Insert(0, "Hello, world!");
 
+            //sb.Append(new char[] { 'D', 'E', 'F' });
 
             // ...AND THIS LINE
 
@@ -58,6 +61,17 @@ public StringBuilder two()
             // 2. After adding the message, use an appropriate StringBuilder method to reverse it
             // WRITE YOUR CODE BETWEEN THIS LINE...
 
+            // Add initially
+            sb.Insert(0, "Hello, world!");
+
+            // Get length of string
+            int sb_len = sb.Length;
+
+            // Reverse string, add it to the end of initial string
+            sb.Append(sb.ToString().Reverse().ToArray());
+
+            // Remove original string using length of original string
+            sb.Remove(0, sb_len);
 
 
             // ...AND THIS LINE
@@ -73,6 +87,8 @@ public StringBuilder three()
             // 2. After adding the message, remove the comma.
             // WRITE YOUR CODE BETWEEN THIS LINE...
 
+            sb.Insert(0, "Hello, world!");
+            sb.Replace(",", "");
 
 
             // ...AND THIS LINE
@@ -88,7 +104,9 @@ public StringBuilder four()
             // 2. After adding the message, replace the word "world" with the word "C#"
             // WRITE YOUR CODE BETWEEN THIS LINE...
 
+            sb.Insert(0, "Hello, world!");
 
+            sb.Replace("world", "C#");
 
             // ...AND THIS LINE