Which of the following statement is correct?

#include<iostream.h> 
struct Tab
{
    short n;
};
int main()
{
    Tab b;
    Tab& rb = b;
    b.n = 5;
    cout << b.n << " " << rb.n << " ";
    rb.n = 8;
    cout << b.n << " " << rb.n;
    return 0; 
}

#include<iostream.h>
long CuriousTabFunction(int x, int y = 5, float z = 5)
{
    return(++x * ++y + (int)++z);
}
int main()
{
    cout<< CuriousTabFunction(20, 10); 
    return 0;
}

#include<iostream.h> 
void MyFunction(int a, int b = 40)
{
    cout<< " a = "<< a << " b = " << b << endl;
}
int main()
{
    MyFunction(20, 30);
    return 0; 
}

#include<iostream.h>
long GetNumber(long int Number)
{
    return --Number;
}
float GetNumber(int Number)
{
    return ++Number;
}
int main()
{
    int x = 20;
    int y = 30;
    cout<< GetNumber(x) << " ";
    cout<< GetNumber(y) ;
    return 0; 
}