//Δ_1006
#include<iostream>
#include<cstdio>
#include<fstream>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<bitset>
#include<cmath>
#include<cstring>
#include<cstdlib>
using namespace std;
typedef long long LL;
typedef double DB;
const int N = 111111;
const int MO = 1e9+7;
void ad(int&x,int y){
    x+=y;
    if(x>=MO)
        x-=MO;
}
int mul(int x,int y){
    return (LL)x*y%MO;
}
int fpow(int x,int y=MO-2){
    int z=1;
    while(y){
        if(y&1)
            z=mul(z,x);
        x=mul(x,x);
        y>>=1;
    }
    return z;
}
int inv[N];
int n,m,a[N],f[N];
vector<int> v[N];
void dfs(int u){
    int i=v[u].size(),x;
    while(i--){
        x=v[u][i];
        if(x==f[u])
            continue;
        f[x]=u;
        dfs(x);
    }
}
int cal(int x){
    if(x==1){
        if(a[x]==1)
            return 0;
        return 1;
    }
    return mul(a[x]-2,inv[a[x]-1]);
}
int main()
{
    int T,i,x,y,o,s;
    for(i=1;i<N;i=i+1)
        inv[i]=fpow(i);
    scanf("%d",&T);
    while(T--){
        scanf("%d%d",&n,&m);
        for(i=1;i<n;i=i+1){
            scanf("%d%d",&x,&y);
            v[x].push_back(y);
            v[y].push_back(x);
            a[x]++,a[y]++;
        }
        dfs(1);
        o=1;
        for(x=f[m];x;x=f[x])
            o=mul(o,inv[a[x]]);
        s=o;
        for(x=f[m];x;x=f[x])
            ad(s,mul(o,cal(x)));
        printf("%d\n",s);
        for(i=1;i<=n;i=i+1){
            v[i].clear();
            a[i]=0;
            f[i]=0;
        }
    }
    return 0;
}