#include <stdio.h>

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