#include <bits/stdc++.h>
using namespace std;
const double eps = 0.00000001;
int main(){
  int T;
  cin >> T;
  for (int i = 0; i < T; i++){
    int N;
    long long K;
    cin >> N >> K;
    K--;
    vector<bool> prime(N + 1, true);
    vector<int> mobius(N + 1, 1);
    for (int j = 2; j <= N; j++){
      if (prime[j]){
        mobius[j] = -1;
        for (int k = j * 2; k <= N; k += j){
          prime[k] = false;
          mobius[k] *= -1;
        }
      }
    }
    for (int j = 2; j * j <= N; j++){
      for (int k = j * j; k <= N; k += j * j){
        mobius[k] = 0;
      }
    }
    double tv = 0, fv = 1000000;
    for (int j = 0; j < 100; j++){
      double mid = (tv + fv) / 2;
      long long ans = 0;
      for (int k = 1; k <= N; k++){
        for (int l = 1; l <= N / k; l++){
          if (mid >= (double) N / k / l){
            ans += mobius[k] * (N / k);
          } else {
            ans += mobius[k] * (int) (mid * l);
          }
        }
      }
      if (ans <= K){
        tv = mid;
      } else {
        fv = mid;
      }
    }
    bool ok = false;
    for (int j = 1; j <= N; j++){
      double x = tv * j;
      if (x <= N + eps){
        if (abs(x - (int) (x + eps)) <= eps){
          cout << (int) (x + eps) << '/' << j << endl;
          ok = true;
          break;
        }
      }
    }
    if (!ok){
      cout << -1 << endl;
    }
  }
}