#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<ll>;

vll PR;

void mobius(vll& A) {
    ll N = A.size();
    for (auto p : PR) {
        if(p>N)break;
        for (ll i = (N - 1) / p; i >= 1; i--) {
            A[p * i] -= A[i];
        }
    }
    return;
}

ll gcd(ll a, ll b) {
    if (b == 0)return a;
    ll c = a;
    while (a % b != 0) {
        c = a % b;
        a = b;
        b = c;
    }
    return b;
}

ll b = (1ll << 42);
ll num(ll p, ll N) {//p/b以下分母がN以下の既約分数
    ll S = 0;
    vll F(N + 1, 0);
    for (ll i = 1; i <= N; i++) {
        F[i] += (p * i) / b;//分母がiで mid/N以下の(既約とは限らない)分数の個数
    }
    //for (ll i = 1; i <= N; i++)cout << F[i] << (i == N ? "\n" : " ");
    mobius(F);
    //for (ll i = 1; i <= N; i++)cout << F[i] << (i == N ? "\n" : " ");
    for (ll i = 1; i <= N; i++)S += F[i];
    return S;
}

int main() {
    ll NINF = 3e5 + 1;
    vector<bool> P(NINF, 1);
    for (int i = 2; i < NINF; i++) {
        if (P[i]) {
            PR.push_back(i);
            for (int j = 2 * i; j < NINF; j += i)P[j] = 0;
        }
    }
    ll T;
    cin >> T;
    while (T--) {
        ll N, K;
        cin >> N >> K;
        ll L = num(b, N) - 1;
        bool INV = 0;
        if (K == L + 1) {
            cout << "1/1" << endl;
            continue;
        }
        if (K > 2 * L + 1) {
            cout << -1 << endl;
            continue;
        }
        if (K > L + 1) {
            INV = 1;
            K = 2 * L - K + 2;
        }
        ll l = 0, r = b+1;
        while (r - l > 1)(num((r + l) / 2, N) < K ? l : r) = (r + l) / 2;
        vll F(N + 1, 0);
        pair<ll, ll> P;
        for (ll i = 1; i <= N; i++) {
            ll a=(r*i)/b;
            if(gcd(a,i)==1)if(a*b>=l*i)P={a,i};
        }
        if (INV)swap(P.first, P.second);
        cout << P.first << "/" << P.second << endl;
    }
}