KingOfNothing

#include<iostream>
#include<stdio.h>
#include<sstream>
#include<string>
#include<string.h>
#include<math.h>
#include<vector>
#include<map>
#include<algorithm>
#include<queue>
#include<set>
#include<stdlib.h>
#include<cmath>
#include<stack>

using namespace std;
#define mod 1000000007
#define pi 2*acos(0)
#define PI 3.141592653589793
#define pb push_back
#define fr(i,a,b) for(i=a;i<=b;i++)
#define frn(i,a,b) for(i=a;i>=b;i--)
unsigned long long fact[1005];

long long int A=1,B=1;
void process()
{
    long long int i,mini,limit;
    if(A<B)
    {
        mini=A;
    }
    else
    {
        mini=B;
    }
    if(mini==2)
    {
        limit=2;
    }
    else
        limit=(sqrt(mini))+1;
    fr(i,2,limit)
    {
        while(((A%i)==0)&&((B%i)==0))
        {
            A=A/i;
            B=B/i;
        }
    }
    //printf("%lld/%lld\n",A,B);
    return ;
}

int main()
{
    long long int tC,nC;
    long long int t,x;
    scanf("%lld",&tC);
    fr(nC,1,tC)
    {
        A=1;
        B=1;
        long long int temp;
        scanf("%lld %lld",&t,&x);
        long long int arr[t+7],i;
        fr(i,1,t)
        {
            scanf("%lld",&temp);
            arr[i]=x-temp;
            A=((A%mod)*(arr[i]%mod))%mod;
            B=((B%mod)*(x)%mod)%mod;
        }
        process();
        if(A==0)
        {
            printf("Case %lld: 0\n",nC);
        }
        else if(A==B)
        {
            printf("Case %lld: 1\n",nC);
        }
        else
        printf("Case %lld: %lld/%lld\n",nC,A,B);
    }
    return 0;
}