#include <iostream>
#include <vector>
#include <climits>
#include <algorithm>
#include <cassert>
#include <cstdio>
#include <fstream>

using namespace std;

#define NFLAT_MAX 100
#define UNDEF (-1)
#define UNREACHABLE (-2)
#define INFTY INT_MAX

class Slope {
public:
	int head, length, effort;

	Slope( int head, int length, int adspeed ) : head(head), length(length) {
		// 60 より出せるときは 60 で押さえておくのがベスト.
		// それ以外の場合はできるだけ 70 に近づくように出し切るべき.
		// e の計算しきより明かである.
		if ( adspeed > 60 )
			effort = length*10;
		else
			effort = length*(70-adspeed);
	}

};


int nflat, nslope;
int source, dest;

vector<Slope> G[NFLAT_MAX+1];
bool visiting[NFLAT_MAX+1];

// Longest Down Path, Smallest Effort Down Path.
int LDP[NFLAT_MAX+1], SEDP[NFLAT_MAX+1];

void recTable( int n ) {
	// YES: There are no cycles.
	assert( !visiting[n] );

	if ( LDP[n] != UNDEF ) return;

	visiting[n] = true;
	for ( int i = 0; i < G[n].size(); i++ ) {
		const Slope &e = G[n][i];

		recTable(e.head);

		if ( LDP[e.head] == UNREACHABLE ) continue;
		LDP[n] = max(LDP[n], LDP[e.head]+e.length);
		SEDP[n] = min(SEDP[n], SEDP[e.head]+e.effort);
	}
	visiting[n] = false;

	if ( LDP[n] == UNDEF ) LDP[n] = UNREACHABLE;
}

void computeTable( int source, int dest ) {
	for ( int n = 1; n <= nflat; n++ ) LDP[n] = UNDEF, SEDP[n] = INFTY, visiting[n] = false;
	LDP[dest] = 0, SEDP[dest] = 0;
	recTable(source);
}

bool isBetter( long long n, long long d,  long long N, long long D ) {
	if ( N == INFTY || n == 0 ) return true;
	return (n*D < N*d);
}

void compute( int u, int dest, int N, int D, int &optN, int &optD ) {
	if ( u == dest ) {
		if ( isBetter(N, D, optN, optD) ) optN = N, optD = D;
		return;
	}

	// pruning.  それ以降の経路に現れる最大の分母和と最小の分子和を加えた
	// 場合が実現可能な最善であることを利用.
	if ( !isBetter(N+SEDP[u], D+LDP[u], optN, optD) ) return;

	for ( int i = 0; i < G[u].size(); i++ ) {
		const Slope &e = G[u][i];
		if ( LDP[e.head] == UNREACHABLE ) continue;
		compute(e.head, dest, N+e.effort, D+e.length, optN, optD);
	}
}

int main() {
	ifstream cin("ski.txt");

	int ntest; cin >> ntest;

	for ( int nt = 0; nt < ntest; nt++ ) {
		cin >> nflat >> nslope;
		cin >> source >> dest;

		for ( int n = 1; n <= nflat; n++ ) G[n].clear();
		for ( int n = 0; n < nslope; n++ ) {
			int tail, head, adspeed, length;
			cin >> tail >> head >> adspeed >> length;
			G[tail].push_back(Slope(head, length, adspeed));
		}

		computeTable(source, dest);

		int optN = INFTY, optD = 1;
		compute(source, dest, 0, 0, optN, optD);

		printf("%.2lf\n", (double)optN/optD);
	}

	return 0;
}