#include <bits/stdc++.h>
using namespace std;

const int MOD = 1e9+7;


const int MAXN = 100010;
struct Edge {
    int to, next;
} edge[MAXN*2];
int head[MAXN], tot;
void init() {
    tot = 0;
    memset(head, -1, sizeof(head));
}
void addedge(int u, int v) {
    edge[tot].to = v;
    edge[tot].next = head[u];
    head[u] = tot++;
}

int dep[MAXN];
int du[MAXN];
int fa[MAXN];
void dfs(int u, int pre) {
    du[u] = 0;
    fa[u] = pre;
    for (int i = head[u]; i != -1 ;i = edge[i].next) {
        int v = edge[i].to;
        if (v == pre) continue;
        du[u]++;
        dep[v] = dep[u]+1;
        dfs(v, u);
    }
}
long long pow_m(long long a, long long n) {
    long long ret = 1;
    long long tmp = a%MOD;
    while (n) {
        if (n&1) ret = ret*tmp%MOD;
        n >>= 1;
        tmp = tmp*tmp%MOD;
    }
    return ret;
}

int main() {
    int T;
    scanf("%d", &T);
    while (T--) {
        int n, m;
        scanf("%d%d", &n, &m);
        init();
        for (int i = 1; i < n; i++) {
            int u, v;
            scanf("%d%d", &u, &v);
            addedge(u, v);
            addedge(v, u);
        }
        dep[1] = 0;
        dfs(1, 1);

        long long tmp0 = 1;
        long long tmp1 = 0;
        int now = m;
        if (now == 1) {
            puts("1");
            continue;
        }

        do {
            now = fa[now];
            if (now != 1) {
            tmp1 = tmp1*pow_m(du[now]+1, MOD-2)%MOD;
            tmp1 = (tmp1 + tmp0*pow_m(du[now]+1, MOD-2)%MOD*pow_m(du[now], MOD-2)%MOD*(du[now]-1)%MOD)%MOD;
            tmp0 = tmp0*pow_m(du[now]+1, MOD-2)%MOD;
            } else {
                tmp1 = tmp1*pow_m(du[now], MOD-2)%MOD;
                tmp1 = (tmp1 + tmp0*pow_m(du[now], MOD-2)%MOD*pow_m(du[now]-1, MOD-2)%MOD*(du[now]-1)%MOD )%MOD;
                tmp0 = tmp0*pow_m(du[now], MOD-2)%MOD;
            }
        } while (now != 1);

        long long ans = (tmp0 + tmp1)%MOD;

        printf("%d\n", (int) ans);
    }
    return 0;
}