Update 1: 
With everyone's help i was able to get:
-A point I would like to make, each int requires for a new role of definition. Have a look below to understand the mistake in answers and the solution in which I was going for.

If possibly can someone help me make this script continuous? By that I mean, after one expression is done and all the solutions are displayed, the user should be able to continue and keep using the script until they want to quit. Basically, how can I loop this whole thing so it does not end after one user input?

```
 #include<stdio.h>
 #include<math.h>
 #include<string.h>

 int gcd(int a, int b) {
    while(0!=b) { int r = a % b; a=b; b=r; }
    return a;
}
 int input(char* prompt) {
    int res;
    printf("%s: ", prompt);
    scanf("%d", &res);
    return res;
}
 main()
 {
    int add,sub,mul,dd;
    int add1,sub1,mul1,dd1;
    int a,b,c,d;
    a=input("Please enter the numerator for your first equation");
    b=input("Please enter the denominator for your first equation");
    c=input("Please enter the numerator for your second equation");
    d=input("Please enter the denominator for your second equation");
    add=(a*d+b*c);
    add1=(b*d);
    int fac = gcd(add, add1);
        add /=fac;
        add1 /=fac;
    printf("\The sum of your fractions is: %d/%d",add,add1);
    sub=(a*d-b*c);
    sub1=(b*d);
    int red = gcd(sub, sub1);
        sub /=red;
        sub1 /=red;
    printf("\nThe difference of your fractions is: %d/%d",sub,sub1);
    mul=(a*c);
    mul1=(b*d);
    int red1 = gcd(mul, mul1);
        mul /=red1;
        mul1 /=red1;
    printf("\nThe product of your fractions is: %d/%d",mul,mul1);
    dd=(a*d);
    dd1=(b*c);
    int red2 = gcd(dd, dd1);
        dd /=red2;
        dd1 /=red2;
    printf("\nThe quotient of your fractions is: %d/%d",dd,dd1);
 }

```