더블릿|dovelet - 여왕 벌/bumblebee

문제

#include <iostream>
 
using namespace std;
 
int main()
{
    double a, b, x, l;
    cin >> a >> b >> x >> l;
    cout.precision(6);
    cout << fixed << l / (a + b) * x;
 
    return 0;
}