Your code will be more simplified as-:
#include<stdio.h>
#define f(x) x*x+x
main()
{
int x;
x=f(8)*f(5);
x=((8*8)+((8*5)*5)+5)
printf("%d",x);
}
Reason-:define simply replaces the replaces the variable unlike a function which execute it.
x=((8*8)+((8*5)*5)+5)=269
here * has more precedence than + and * i left associate ,so it will be executed in this order.