so i am given this code

insert
Code:
#include <stdio.h>
 
int function2(int a, int b);
 
int main() {   
    int a = 1, b = 2;
    b = function2(a,b);
    printf("a = %d, b = %d\n", a, b);
    a = function2(b,a);
    printf("a = %d, b = %d\n", a, b);
   
    return 0;
}
 
int function2(int a, int b) {
    int temp = a+b;
    a = 3*temp - (2*b)%15;
    b = a%temp;
    printf("a = %d, b = %d\n", a, b);
    return 2*a - b;
}

and then this question

3) What is the first line of output produced by this program?

A) a = 2, b = 5
B) a = 5, b = 2
C) a = 5, b = 1
D) a = 5, b =
E) a = 3, b = 5


I know the answer is B but what confuses me is how to get that answers?