#include<iostream>
#include<stdio.h>
using namespace std;

int main() {

  double A, B, P, Q, R;
  double t, b;
  double time;

  cin>>A>>B>>P>>Q>>R;

  t = P * B;
  b = Q * (B-A);
  t = t-b;
  time = (t / (Q+R)) + B;

  printf("%.12f\n", time);

  return 0;
}

