#include <bits/stdc++.h>   using namespace std;   int main() {     long long n, a, b, c, ans, boby, apu;     cin >> n;     while (n--) {       cin >> a >> b >> c >> ans;       boby = b - a;       apu = c + ans;       if (boby % apu == 0) {         cout << boby / apu << endl;       } else         cout <<  -1  << endl;     }     return 0;   }   