import java.util.*;
import java.lang.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
class Main
{
	public static void main (String[] args) throws IOException
	{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 
        int ile = Integer.parseInt(br.readLine());
 
        for (int j=0; j < ile; j++) {
            int a[] = new int[2];
            String line = br.readLine();
            String[] s = line.trim().split(" ");
            for (int i = 0; i < 2; i++) {
                a[i] = Integer.parseInt(s[i]);
            }
            System.out.println(2 * a[0] * a[1] / (a[0] + a[1]));
        }
	}
}

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Mgo1MCA1MAo2MCA0MA==

2
50 50
60 40