HDU 2548.两军交锋

#include <iostream>
#include <queue>
#include <string>
#include <algorithm>
#include <math.h>

#define INF 0x3f3f3f3f
#define eps 1e-8

using namespace std;

int main() {
int t;
cin >> t;
while (t--) {
double u, v, w, l;
cin >> u >> v >> w >> l;
double ans = (l / (u + v))*w;
printf("%.3lf\n", ans);
}

//system("pause");
}