In my first function "compute" if I want to return the values of "sum" and "sum_of_squares" in main what do I have to do?

Code:`//Name: Joseph Valenzuela`

//Date: March 11, 2003

//Purpose: To design and implement my own program for project1.

#include <iostream.h> // For output to the screen and input from user

#include <fstream.h> // To allow input and output streams

#include <stdlib.h> // Contains exit function

#include <math.h> // Contains square root function

double compute();

//Precondition:

//Postcondition:

double mean(double xnum, double sum);

//Precondition:

//Postcondition:

double deviation(double var);

//Precondition:

//Postcondition:

double variance(double sum_of_squares, double xnum, double avg);

//Precondition:

//Postcondition:

void main()

{

double xnum,sum,avg;

ifstream input_data;

cout <<"\nWELCOME TO THE BASIC STATISTICS PACKAGE!\n";

cout << "Enter amount of numbers to be evaluated: ";

cin >> xnum;

sum = compute();

avg = mean(xnum, sum);

cout << sum << endl;

cout << avg << endl;

}

double compute()

{

double sum=0, sum_of_squares=0, in_num=0, count=0;

ifstream input_data;

input_data.open("stats.dat");

if (input_data.fail())

{

cout <<"Input file could not be opened.\n";

exit(1);

}

input_data >> in_num;

while (!input_data.eof())

{

count++;

sum += in_num;

sum_of_squares += in_num*in_num;

input_data >> in_num;

}

return(sum);

return (sum_of_squares);

}

double mean(double xnum, double sum)

{

double avg=0;

avg = sum/xnum;

return(avg);

}

double variance(double sum_of_squares, double xnum, double avg)

{

double var=0;

var = (sum_of_squares/xnum) - (avg*avg);

return(var);

}

double deviation(double var)

{

double dev;

dev = sqrt(var);

return(dev);

}