#include<stdio.h>
int main()
{
    int T;
    scanf("%d",&T);
    int i;
    int count=0;
    long long x,y,a,b;
    for(i=0;i<T;i++)
    {
        scanf("%lld%lld%lld%lld",&x,&y,&a,&b);
    }
    while(x<y)
  {

    x=x+a;
    y=y-b;
    count++;
    if(x-y==0)
  printf("%d",count);
    else if(x-y!=0)
            printf("-1");

}

    return 0;
}