#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    long long int x, y, a, b;
    cin >> x >> y >> a >> b;
    if (((y - x) % (a + b) == 0)) {
      cout << ((y - x) / (a + b)) << "\n";
    } else
      cout << -1 << "\n";
  }
  return 0;
}
