#include<stdio.h>
int main()
{

    int t,j;

    long long int  x, y, a, b,l,s1,s2,c=0 ;
    scanf("%d",&t);
    for(j=1; j<=t; j++)
    {
        scanf("%lld %lld %lld %lld",&x,&y,&a,&b);
        l=y-x;
        int i=0;
        while(l>c)
        {
            i++;
            s1=a*i;
            s2=b*i;
            c=s1+s2;

        }

        if(l==c)
        {
            printf("%d\n",i);
        }
          else printf("-1\n");
    }
    return 0;
}