#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,b) for(int i=0;i<b;i++)
#define rrep(i,b) for(int i=b-1;i>=0;i--)
#define rep1(i,b) for(int i=1;i<b;i++)
#define repx(i,x,b) for(int i=x;i<b;i++)
#define rrepx(i,x,b) for(int i=b-1;i>=x;i--)
#define fore(i,a) for(auto i:a)
#define fore1(i,a) for(auto &i:a)
#define rng(x) (x).begin(), (x).end()
#define rrng(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define fi first
#define se second
#define pcnt __builtin_popcountll

using namespace std;
using namespace atcoder;

using ll = long long;
using ld = long double;
template<typename T> using mpq = priority_queue<T, vector<T>, greater<T>>;
template<typename T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<typename T> bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> ll sumv(const vector<T>&a){ll res(0);for(auto&&x:a)res+=x;return res;}
bool yn(bool a) { if(a) {cout << "Yes" << endl; return true;} else {cout << "No" << endl; return false;}}
#define dame { cout << "No" << endl; return;}
#define dame1 { cout << -1 << endl; return;}
#define cout2(x,y) cout << x << " " << y << endl;
#define coutp(p) cout << p.fi << " " << p.se << endl;
#define out cout << ans << endl;
#define outd cout << fixed << setprecision(20) << ans << endl;
#define outm cout << ans.val() << endl;
#define outv fore(yans , ans) cout << yans << "\n";
#define outdv fore(yans , ans) cout << yans.val() << "\n";
#define coutv(v) {fore(vy , v) {cout << vy << " ";} cout << endl;}
#define coutv2(v) fore(vy , v) cout << vy << "\n";
#define coutvm(v) {fore(vy , v) {cout << vy.val() << " ";} cout << endl;}
#define coutvm2(v) fore(vy , v) cout << vy.val() << "\n";
using pll = pair<ll,ll>;using pil = pair<int,ll>;using pli = pair<ll,int>;using pii = pair<int,int>;using pdd = pair<ld,ld>;
using tp = tuple<int ,int ,int>;
using vi = vector<int>;using vd = vector<ld>;using vl = vector<ll>;using vs = vector<string>;using vb = vector<bool>;
using vpii = vector<pii>;using vpli = vector<pli>;using vpll = vector<pll>;using vpil = vector<pil>;
using vvi = vector<vector<int>>;using vvl = vector<vector<ll>>;using vvs = vector<vector<string>>;using vvb = vector<vector<bool>>;
using vvpii = vector<vector<pii>>;using vvpli = vector<vector<pli>>;using vvpll = vector<vpll>;using vvpil = vector<vpil>;
using mint = modint998244353;
//using mint = modint1000000007;
//using mint = dynamic_modint<0>;
using vm = vector<mint>;
using vvm = vector<vector<mint>>;
vector<int> dx={1,0,-1,0,1,1,-1,-1},dy={0,1,0,-1,1,-1,1,-1};
ll gcd(ll a, ll b) { return a?gcd(b%a,a):b;}
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;}
#define yes {cout <<"Yes"<<endl;}
#define yesr { cout <<"Yes"<<endl; return;}
#define no {cout <<"No"<<endl;}
#define nor { cout <<"No"<<endl; return;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#ifdef MY_LOCAL_DEBUG
#define show(x) cerr<<#x<<" = "<<x<<endl
#define showp(p) cerr<<#p<<" = "<<p.fi<<" : "<<p.se<<endl
#define show2(x,y) cerr<<#x<<" = "<<x<<" : "<<#y<<" = "<<y<<endl
#define show3(x,y,z) cerr<<#x<<" = "<<x<<" : "<<#y<<" = "<<y<<" : "<<#z<<" = "<<z<<endl
#define show4(x,y,z,x2) cerr<<#x<<" = "<<x<<" : "<<#y<<" = "<<y<<" : "<<#z<<" = "<<z<<" : "<<#x2<<" = "<<x2<<endl
#define test(x) cout << "test" << x << endl
#define showv(v) {fore(vy , v) {cout << vy << " ";} cout << endl;}
#define showv2(v) fore(vy , v) cout << vy << "\n";
#define showvm(v) {fore(vy , v) {cout << vy.val() << " ";} cout << endl;}
#define showvm2(v) fore(vy , v) cout << vy.val() << "\n";
#else
#define show(x)
#define showp(p)
#define show2(x,y)
#define show3(x,y,z)
#define show4(x,y,z,x2)
#define test(x)
#define showv(v)
#define showv2(v)
#define showvm(v)
#define showvm2(v)
#endif

struct Sieve {
    int n;
    vector<int> f, primes;
    Sieve(int n=1):n(n), f(n+1) { //初期化、f[x] = (xの最も小さい素因数)
        f[0] = f[1] = -1;
        for (ll i = 2; i <= n; ++i) {
            if (f[i]) continue;
            primes.push_back(i);
            f[i] = i;
            for (ll j = i*i; j <= n; j += i) {
                if (!f[j]) f[j] = i;
            }
        }
    }
    bool isPrime(int x) { return f[x] == x;} //素数判定
    vector<int> factorList(int x) {//素因数分解、xの素因数を小さいものから個数分列挙
        vector<int> res;
        while (x != 1) {
            res.push_back(f[x]);
            x /= f[x];
        }
        return res;
    }
    vector<pii> factor(int x) {//素因数分解その２、xの素因数を小さいものから(素因数、個数)の形で列挙
        vector<int> fl = factorList(x);
        if (fl.size() == 0) return {};
        vector<pii> res(1, pii(fl[0], 0));
        for (int p : fl) {
            if (res.back().first == p) {
                res.back().second++;
            } else {
                res.emplace_back(p, 1);
            }
        }
        return res;
    }
    vector<pli> factor(ll x) {//素因数分解その２-２、xがllの場合
        vector<pli> res;
        for (int p : primes) {
            int y = 0;
            while (x%p == 0) x /= p, ++y;
            if (y != 0) res.emplace_back(p,y);
        }
        if (x != 1) res.emplace_back(x,1);
        return res;
    }
    ll totient(ll x){
        ll den = 1,num = 1;
        if (x<=n){
            vpii v = factor((int)x);
            fore(y , v){
                den *= y.fi;
                num *= (y.fi-1);
            }
        }else{
            vpli v = factor(x);
            fore(y , v){
                den *= y.fi;
                num *= (y.fi-1);
            }
        }
        assert(x%den==0);
        ll ret = x/den*num;
        return ret;
    }

///////////////// 以下、約数/倍数 ゼータ・メビウス変換 ////////////////

    // 以下、約数変換
    template <typename T>
    void div_zeta_trans(vector<T> &a) {
        int n = sz(a)-1;
        fore(p, primes) {
            if (p > n) break;
            for (int i = 1; i * p <= n; ++i) a[i * p] += a[i];
        }
    }
    template <typename T>
    void div_mobius_trans(vector<T> &a) {
        int n = sz(a)-1;
        fore(p, primes) {
            if (p > n) break;
            for (int i = n / p; i > 0; --i) a[i * p] -= a[i];
        }
    }
    template <typename I, typename T>
    void div_zeta_trans(map<I, T> &a) {
        for (auto p = a.rbegin(); p != a.rend(); p++) {
            fore(y, a) {
                if (p->fi == y.fi) break;
                if (p->fi % y.fi == 0) p->se += y.se;
            }
        }
    }
    template <typename I, typename T>
    void div_mobius_trans(map<I, T> &a) {
        fore(y, a) {
            for (auto p = a.rbegin(); p != a.rend(); p++) {
                if (y.fi == p->fi) break;
                if (p->fi % y.fi == 0) p->se -= y.se;
            }
        }
    }

    // 以下、倍数変換
    template <typename T>
    void mul_zeta_trans(vector<T> &a) {
        int n = sz(a)-1;
        fore(p, primes) {
            if (p > n) break;
            for (int i = n / p; i > 0; --i) a[i] += a[i * p];
        }
    }
    template <typename T>
    void mul_mobius_trans(vector<T> &a) {
        int n = sz(a)-1;
        fore(p, primes) {
            if (p > n) break;
            for (int i = 1; i * p <= n; ++i) a[i] -= a[i * p];
        }
    }
    template <typename I, typename T>
    void mul_zeta_trans(map<I, T> &a) {
        fore(y, a) {
            for (auto p = a.rbegin(); p != a.rend(); p++) {
                if (y.fi == p->fi) break;
                if (p->fi % y.fi == 0) y.se += p.se;
            }
        }
    }
    template <typename I, typename T>
    void mul_mobius_trans(map<I, T> &a) {
        for (auto p1 = a.rbegin(); p1 != a.rend(); p1++) {
            for (auto p2 = a.rbegin(); p2 != p1; p2++) {
                if (p2->fi % p1->fi == 0) p1->se += p2.se;
            }
        }
    }
} sieve(1e6);

// エラストテネスの篩
// .primes : n以下の素数を小さい順で格納しているベクトル。
// .isPrime(int x) : xの素数判定。boolで返す
// .factorList(int x) : xの素因数分解。xの素因数を小さいものから個数分列挙。vector<int>で返す。
// .factor(int x) : 素因数分解その２、xの素因数を小さいものからpair<int int>{素因数、個数}の形で列挙。vector<pii>で返す。xはllでもok。
// 宣言方法 : n=1e6(デフォルト)で初期化している。
// 注意点 : factorList、factorは呼び出し毎に約数個分の計算時間がかかってしまうため、何度も呼び出すときは予め別の配列に格納しておくこと。

// 約数/倍数 ゼータ・メビウス変換
// f = Σg : g → f をゼータ変換、f → g をメビウス変換
// map<I,T>はI が idx T が 関数値


void solve(){
    ll n,k; cin>>n>>k;
    ld l = 0,u = n+2;

    ll cnt = 0;
    rep1(i,n+1) cnt += sieve.totient(i);
    cnt--;
    if (2*cnt+1<k) dame1;
    if (cnt+1==k){
        cout << "1/1" << endl;
        return;
    }
    ll temp = k;
    if (k>cnt) k = 2*cnt+2-k;

    auto check = [&](ld mid)->bool{
        ll cnt = 0;
        vl g(n+1);
        auto f = [&](int a,int b)->bool{
            assert(b>0);
            ld p = (ld)b/a;
            return (p<=mid);
        };

        repx(i,2,n+1){
            int l=1,u=i-1;
            if (f(i,u)){
                g[i] = u;
                continue;
            }
            if (!f(i,l)) continue;
            while(u-l>1){
                int mi = (l+u)/2;
                if (f(i,mi)) l = mi;
                else u = mi;
            }
            g[i] = l;
        }
        sieve.div_mobius_trans(g);
        cnt = sumv(g);
        return (cnt>=k);
    };

    while(u-l>1e-13){
        ld mid = (u+l) / 2;
        if (check(mid)) u = mid;
        else l = mid;
    }

    pii ans;
    ld mn = 1e9;
    rep1(i,n+1){
        auto f = [&](int a,int b)->bool{
            assert(b>0);
            ld p = (ld)b/a;
            return (p<=u);
        };
        auto upd = [&](int x)->void{
            if (x>n) return;
            ld p = (ld)x/i;
            p = abs(p-u);
            if (chmin(mn,p)){
                ans = {i,x};
            }
            return;
        };
        int li=1,ui=n;
        if (!f(i,li)){
            upd(li);
            continue;
        }
        while(ui-li>1){
            int mid = (li+ui)/2;
            if (f(i,mid)) li = mid;
            else ui = mid;
        }
        upd(li);
        upd(li+1);
    }
    ll d = gcd(ans.fi,ans.se);
    ans.fi /= d;
    ans.se /= d;
    if (temp>cnt) swap(ans.fi,ans.se);
    string s;
    s += to_string(ans.se);
    s += '/';
    s += to_string(ans.fi);
    cout << s << endl;

    return;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    cin>>t;

    rep(i,t){
        solve();
    }

    return 0;
}