#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;
}

void solve()
{
  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";
      return;
    }
    tot = dp[1];
  }

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

int main()
{
  int t;
  cin >> t;
  while (t--)
  {
    solve();
  }
  cout << endl;
}