#include <stdio.h>

int main () {
  int t = 0;
  
  int res = 0;
  
  long long ps[300001][10] = {};
  int pcnt[300001] = {};
  long long fr[300000][2] = {};
  
  for (int i = 2; i <= 300000; i++) {
    if (pcnt[i] <= 0) {
      ps[i][0] = (long long)i;
      pcnt[i] = 1;
      for (int p = 2; i*p <= 300000; p++) {
        ps[i*p][pcnt[i*p]] = i;
        pcnt[i*p]++;
      }
    }
  }
  
  res = scanf("%d", &t);
  while (t > 0) {
    long long n = 0LL;
    long long k = 0LL;
    long long rcnt = 1LL;
    res = scanf("%lld", &n);
    res = scanf("%lld", &k);
    rcnt = n*n;
    for (long long i = 1LL; i <= n; i += 1LL) {
      for (int j = 1; j < (1<<pcnt[(int)i]); j++) {
        int bcnt = 0;
        long long p = 1LL;
        for (int l = 0; l < pcnt[(int)i]; l++) {
          if ((j&(1<<l)) > 0) {
            p *= ps[(int)i][l];
            bcnt++;
          }
        }
        if (bcnt%2 == 1) {
          rcnt += n/p;
        } else {
          rcnt -= n/p;
        }
      }
    }
    if (rcnt < k) {
      printf("-1\n");
    } else {
      long long ans[2] = {};
      long long l = 0LL;
      long long r = (1LL<<19LL);
      long long div = 1LL;
      long long lcnt = 0LL;
      int frcnt = 0;
      while (div <= n) {
        long long nxt = l+r;
        long long cnt = 0LL;
        if (nxt%2LL == 1LL) {
          div *= 2LL;
          l *= 2LL;
          r *= 2LL;
        } else {
          nxt /= 2LL;
        }
        for (long long i = 1LL; i <= n; i += 1LL) {
          long long d = (nxt*i)/div;
          long long diff = 0LL;
          if (d > n) {
            d = n;
          }
          for (int j = 1; j < (1<<pcnt[(int)i]); j++) {
            int bcnt = 0;
            long long p = 1LL;
            for (int l = 0; l < pcnt[(int)i]; l++) {
              if ((j&(1<<l)) > 0) {
                p *= ps[(int)i][l];
                bcnt++;
              }
            }
            if (bcnt%2 == 1) {
              diff += d/p;
            } else {
              diff -= d/p;
            }
          }
          cnt += d-diff;
        }
        if (cnt < k) {
          l = nxt;
          lcnt = cnt;
        } else {
          r = nxt;
          rcnt = cnt;
        }
      }
      printf("%lld/%lld\n", ans[0], ans[1]);
    }
    t--;
  }
  
  return 0;
}