#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> P;
#define rep(i, n) for (int i = 0; i < n; i++)
#define int long long
signed main(signed argc, char* argv[]) {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int a,b,p,q,r;
	cin>>a>>b>>p>>q>>r;
	double time=(double)(b*p-(b-a)*q)/(q+r)+b;
	printf("%.16lf",time);
}

