C :

#include<stdio.h>

int main()
{
	int n;
	double x1,x2,x3,y1,y2,y3;
	while(scanf("%d",&n)!=EOF,n)
	{
		while(n--)
		{
			scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
			printf("%.1lf %.1lf\n",(x1+x2+x3)/3,(y1+y2+y3)/3);
		}
	}
	return 0;
}

C++ :

#include<stdio.h>

int main()
{
	int n;
	double x1,x2,x3,y1,y2,y3;
	while(scanf("%d",&n)!=EOF,n)
	{
		while(n--)
		{
			scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
			printf("%.1lf %.1lf\n",(x1+x2+x3)/3,(y1+y2+y3)/3);
		}
	}
	return 0;
}

Java :

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        while(in.hasNextInt()){
        int n=in.nextInt();
        if(n==0) break;
        double[] x=new double[3];
         double[] y=new double[3];
        for(int i=1;i<=n;i++){
            double ave1=0,ave2=0;
          for(int j=0;j<3;j++){
               x[j]=in.nextDouble();
               y[j]=in.nextDouble();
            }
            for(int k=0;k<3;k++){
                ave1+=x[k];
                 ave2+=y[k];
                }
                ave1=ave1/3.0;
                 ave2=ave2/3.0;
                 System.out.printf("%.1f",ave1);
                 System.out.print(" ");
                 System.out.printf("%.1f\n",ave2);
                }
            }
        }
    }