What is the output of this code? Can someone please explain me this how?

Question

void sum(int a, int b, int &c)
{
a=b+c;
b=a+c;
c=a+b;
}
int main()
{
int x=2,y=3;
sum(x,y,y);
cout<<x<<y;
}

Answer 1

a=3+3=6
b=6+3=9
c=6=9=15

&c is in parameters, so it points to y. So, the value of y gets changed to 15 while x remains 2

Output:215