Just need a detailed explanation on how the answers were attained.

Parameters: What does the following program print?#include <stdio.h>void f1(int *a, int *b){    *a +=*b;}void f2(int *a, int *b){    *a-=*b;}void f3(int *a, int *b){     int i;     for (i = 0; i < 3; i++) {        f1(a, b);      printf(a= %i, *a);}}void main () { int x =6; int y =2; int z =7; f2 (&x, &y); f3 (&x, &z); printf(\nx=%i, y=%i, z=%i, x, y, z);}ANSWER IS:a =11 a=18 a=25x=25 y=2 z=7