#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint1000000007;
const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
//const bool debug = false;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<long long,long long>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
struct Edge {
	int to;
	mint cost;
	Edge(int _to, mint _cost) :to(_to), cost(_cost) {}
};
struct Data {
	mint sump;
	mint sum;
	mint count;
	Data() :sump(0), sum(0), count(0) {}
	Data(mint _sump, mint _sum, mint _count) :sump(_sump), sum(_sum), count(_count) {}
};
vector<Edge>g[200005];
vector<Data>dp(200005);
vector<Data>dpR(200005);
void dfs(int v, int p = -1) {
	Data val = { 0,0,0 };
	for (auto e : g[v]) {
		if (p == e.to)continue;
		dfs(e.to, v);
		val.sump += dp[e.to].sump + dp[e.to].sum * e.cost * 2 + e.cost * e.cost * (dp[e.to].count + 1);
		val.sum += dp[e.to].sum + e.cost * (dp[e.to].count + 1);
		val.count += dp[e.to].count + 1;
	}
	dp[v] = val;
}
void dfsR(int v, int p = -1, mint cost = 0) {
	dpR[v] = dp[v];
	if (-1 != p) {
		Data sub = dpR[p];
		sub.sump -= dp[v].sump + dp[v].sum * cost * 2 + cost * cost * (dp[v].count + 1);
		sub.sum -= dp[v].sum + cost * (dp[v].count + 1);
		sub.count -= dp[v].count + 1;

		dpR[v].sump += sub.sump + sub.sum * cost * 2 + cost * cost * (sub.count + 1);
		dpR[v].sum += sub.sum + cost * (sub.count + 1);
		dpR[v].count += sub.count + 1;
	}
	for (auto e : g[v]) {
		if (p == e.to)continue;
		dfsR(e.to, v, e.cost);
	}
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	rep(i, n - 1) {
		int a, b, c; cin >> a >> b >> c; a--; b--;
		g[a].push_back({ b,c });
		g[b].push_back({ a,c });
	}
	dfs(0);
	//rep(i, n)cout << dp[i].sump.val() << " " << dp[i].sum.val() << " " << dp[i].count.val() << endl;
	dfsR(0);
	//rep(i, n)cout << dpR[i].sump.val() << " " << dpR[i].sum.val() << " " << dpR[i].count.val() << endl;
	mint ans = 0;
	rep(i, n)ans += dpR[i].sump;
	ans *= inv_mod(2, mod);
	cout << ans.val() << endl;
	return 0;
}