#include <iostream>
using std::cout;
using std::cin;
using std::endl;
int main()
{
double miles;
double gallons;
double gallons_sum=0;
double miles_sum=0;
while (gallons !=-1.0){
cout<<"Enter the gallons used (-1 to end): ";
cin>>gallons;
if (gallons =-1.0)
break;
cout<<"Enter the miles driven: ";
cin>>miles;
cout<<"The average for this time was "<<miles/gallons<<endl;
gallons_sum+=gallons;
miles_sum+=miles;
}
cout<<"The total average is "<<miles_sum/gallons_sum<<endl;