/* Exercise 3.17 Solution */
#include <stdio.h>

void
main ()
{
   float gallons, miles, totalGallons = 0.0;
   float totalMiles = 0.0, totalAverage;

   printf ("Enter the gallons used (-1 to end): ");
   scanf ("%f", &gallons);

   while (gallons != -1.0) {
      totalGallons += gallons;

      printf ("Enter the miles driven: ");
      scanf ("%f", &miles);
      totalMiles += miles;

      printf ("The Miles / Gallon for this tank was %f\n\n", miles / gallons);

      printf ("Enter the gallons used (-1 to end): ");
      scanf ("%f", &gallons);
   }

   totalAverage = totalMiles / totalGallons;
   printf ("\nThe overall average Miles/Gallon was %f\n", totalAverage);
}