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); }