#include <bits/stdc++.h>   using namespace std;   int main() {     long long t, x, y, a, b;     scanf( %lld , &t);     while (t--) {       scanf( %lld %lld %lld %lld , &x, &y, &a, &b);       bool yes = false;       int i = 0;       int tens = 1000000;       while (x <= y) {         if (x == y) {           yes = true;           break;         }         while (x + a * tens > y - b * tens && tens > 1) tens /= 10;         x += tens * a;         y -= tens * b;         i += tens;       }       printf( %d n , yes ? i : -1);     }     return 0;   }   