Why the output is 7?

Question

#include <stdio.h>
#define sqr(x) x*x
int main() {
printf ("%d",sqr(3+1));
}
https://code.sololearn.com/cp3QNF1nfpZI/?ref=app

Answer 1

x is replaced with "3+1". 3+1*3+1 = 7.

==> #define sqr(x) (x)*(x)
==> (3+1)*(3+1) = 16