#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main () {
    int T;
    cin >> T;
    vector<vector<int>> X(300030);
    for (int i = 1; i <= 300000; i ++) {
        for (int j = 1; i * j <= 300000; j ++) {
            X[i * j].push_back(i);
        }
    }
    int meb[300030];
    fill(meb, meb + 300030, -2);
    meb[1] = 1;
    for (int i = 2; i <= 300000; i ++) {
        if (meb[i] == -2) {
            meb[i] = -1;
        }
        for (int j = 2; i * j <= 300000; j ++) {
            meb[i * j] *= -1;
            if (j % i == 0) {
                meb[i * j] = 0;
            }
        }
    }
    while (T --) {
        ll N, K;
        cin >> N >> K;
        if (N == 1) {
            puts("1/1");
            continue;
        }
        double l = 0, r = N + 1;
        bool ok = false;
        while(true) {
            double mu = (l + r) / 2;
            ll sum = 0;
            for (ll m = 1; m <= N; m ++) {
                ll n = min(N, (ll)(mu * m));
                for (auto a : X[m]) {
                    sum += (n / a) * meb[a];
                }
            }
            if (sum <= K) {
                l = mu;
            } else {
                r = mu;
            }
            if (sum == K) {
                ok = true;
                break;
            }
            if (l > N) {
                break;
            }
        }
        if (ok) {
            ll s = 0, b = 1;
            for (ll m = 1; m <= N; m ++) {
                ll a = (ll)(m * l);
                a = min(a, N);
                if (b * a >= m * s) {
                    s = a; b = m;
                }
            }
            printf("%lld/%lld\n", s, b);
        } else {
            puts("-1");
        }
    }
}