import java.io.*;
 
public class Main
{
    public static void main(String[] args) throws IOException
    {
        try
        {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 
			int tests = Integer.parseInt(br.readLine());
 
            while (tests-- > 0)
            {
                int v1 = Integer.parseInt(br.readLine());
                int v2 = Integer.parseInt(br.readLine());
                System.out.println(2 * v1 * v2 / (v1 + v2));
            }
        }
        catch (Exception e)
        {
            System.exit(0);
        }
    }
}

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Mgo1MCA1MAo2MCA0MA==

2
50 50
60 40