C# Reference type assignment VS value type assignment

Question

I understand the theoretical concept that assigning one reference type variable to another, only the reference is copied, not the object. assigning one value type variable t

Answer 1

//Reference Type

        StringBuilder sb1 = new StringBuilder();
        StringBuilder sb2 = new StringBuilder();
        sb2 = sb1;
        sb1.Append("hello");
        sb1.Append("world");
        Console.WriteLine(sb2);
        // Output Hello World


        // value Type
        int x=100;            
        int y = x;
        x = 30;            
        Console.WriteLine(y);

        // Out put 100 instead of 30