#include <bits/stdc++.h>

using namespace std;

struct Fast
{
  Fast()
  {
    std::cin.tie(0);
    ios::sync_with_stdio(false);
  }
} fast;

#define rep(i, a, b) for (int i = (a); i < (int)(b); i++)
#define rrep(i, a, b) for (int i = (int)(b)-1; i >= (a); i--)
#define ll long long

template <typename T>
bool chmax(T &a, const T &b)
{
  if (a < b)
  {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
bool chmin(T &a, const T &b)
{
  if (a > b)
  {
    a = b;
    return true;
  }
  return false;
}

int main()
{
  int t;
  cin >> t;
  while (t--)
  {
    ll n, k;
    cin >> n >> k;

    vector<ll> dp(n + 1, 0);
    ll tot = 0;
    {
      for (int i = 1; i <= n; i++)
        dp[i] = (n / i) * (n / i);
      for (ll i = n; i >= 1; i--)
        for (ll j = i * 2; j <= n; j += i)
          dp[i] -= dp[j];
      if (dp[1] < k)
      {
        cout << -1 << "\n";
        continue;
      }
      tot = dp[1];
    }

    if (k == (tot + 1) / 2)
    {
      cout << "1/1\n";
      continue;
      ;
    }

    bool inv = false;
    if (k > (tot + 1) / 2)
    {
      k = tot - k + 1;
      inv = true;
    }

    {
      ll l = 0, r = n * n;
      while (r - l > 1)
      {
        ll x = (l + r) / 2;
        for (int i = 1; i <= n; i++)
        {
          dp[i] = 0;
          for (int a = i; a <= n; a += i)
            dp[i] += min(n, a * x / (n * n)) / i;
        }
        for (ll i = n; i >= 1; i--)
          for (ll j = i * 2; j <= n; j += i)
            dp[i] -= dp[j];
        if (dp[1] < k)
          l = x;
        else
          r = x;
      }
      for (long a = 1; a <= n; a++)
      {
        long x = a * l / n / n + 1;
        long y = a * r / n / n;
        if (x == y)
        {
          if (!inv)
          {
            cout << y << "/" << a << "\n";
          }
          else
          {
            cout << a << "/" << y << "\n";
          }
          break;
        }
      }
    }
  }
  cout << endl;
}