HDOU/HDU 2548 两军交锋(看你的思维~)

import java.util.Scanner;

/**
 * 
 * @author 陈浩翔
 *
 * 2016-5-16
 */
public class Main{

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int t =sc.nextInt();
        while(t-->0){
            double u =sc.nextDouble();
            double v =sc.nextDouble();
            double w =sc.nextDouble();
            double l =sc.nextDouble();
            double time = l/(u+v);
            System.out.printf("%.3f",time*w);
            System.out.println();
        }

    }

}