#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=2167167167167167167;
const int INF=2100000000;
const int mod=998244353;
#define rep(i,a,b) for (ll i=a;i<b;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){assert(!a.empty());T ans=a[0]-a[0];for(auto &x:a) ans+=x;return ans;}

//Mobius(n)=0  exists p n|p*p
//         =-1  if n=p_1*p_2*...*p_{2a+1}
//         =1 if n=p_1*p_2*...*p_{2a}
std::vector<int> Mobius(int N){
    std::vector<int> p(N+1,-2);
    p[1]=1;
    for(int i=2;i<=N;i++){
        if(p[i]!=-2) continue;
        p[i]=-1;
        for(int j=i*2;j<=N;j+=i){
            if(p[j]==-2) p[j]=-1;
            else p[j]*=-1;
        }
        if(N/i<i) continue;
        for(int j=i*i;j<=N;j+=i*i) p[j]=0;
    }
    for(int i=1;i<=N;i++){
        if(p[i]==-2) p[i]=-1;
    }
    return p;
}


void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	cin>>t;
	rep(i,0,t) solve();
}

void solve(){
	ll N,K;
    cin>>N>>K;
    vector<vector<int>> table(N+1);
    auto M=Mobius(N);
    rep(i,1,N+1){
        for(int j=i;j<=N;j+=i) table[j].push_back(i);
    }
    int C=0;
    vector<ll> q(N+1,-1);
    vector<ll> r(N+1);
    auto calc=[&](ll A,ll B)->ll{
        C++;
        vector<ll> p(1+N);
        rep(i,1,N+1) p[i]=min(N,(A*i)/B);
        ll res=0;
        rep(i,1,N+1){
            if(p[i]!=q[i]){
                r[i]=0;
                for(auto x:table[i]) r[i]+=M[x]*(p[i]/x);
            }
            res+=r[i];
        }
        swap(p,q);
        return res;
    };
    if(calc(N,1)<K){
        cout<<"-1\n";
        return;
    }
    bool rev=0;
    auto out=[&](ll a,ll b)->void{
        //cout<<C<<endl;
        if(rev) swap(a,b);
        cout<<a<<"/"<<b<<"\n";
    };
    if(calc(N,1)==K){
        out(N,1);
        return;
    }
    if(K==1){
        out(1,N);
        return;
    }
    ll h=calc(1,1);
    if(h==K){
        out(1,1);
        return;
    }
    pair<ll,ll> L={1,N},R={N,1};
    if(h>K) R={1,1};
    else{
        R={1,1};
        K=2*h-K;
        rev=1;
    }
    while(true){
        pair<ll,ll> med={-1,-1};
        rep(i,1,N+1){
            ll X=(L.first*i+L.second)/L.second;
            ll n_X=max(1ll,X);
            ll Y=(i*(R.first)-1)/R.second;
            ll n_Y=min(N,Y);
            if(n_X<=n_Y){
                med={((L.first+R.first)*i+(L.second+R.second)/2)/(L.second+R.second),i};
                chmax(med.first,n_X);
                chmin(med.first,n_Y);
                break;
            }
        }
        //cout<<L.first<<" "<<L.second<<" "<<R.first<<" "<<R.second<<endl;
        assert(med.first!=-1);
        auto tmp=calc(med.first,med.second);
        if(tmp==K){
            out(med.first,med.second);
            return;
        }
        if(tmp<K) L=med;
        else R=med;
    }
}