(Gas Mileage) Drivers are concerned with the mileage obtained by their automobiles. One driver has kept track of several tankfuls of gasoline by recording miles driven and gallons used for each tankful. Develop a program that will input the miles driven and gallons used for each tankful. The program should calculate and display the miles per gallon obtained for each tankful. After processing all input information, the program should calculate and print the combined miles per gallon obtained for all tankfuls. Here is a sample input/output dialog:

Enter the gallons used (-1 to end): 12.8 Enter the miles driven: 287 The miles/gallon for this tank was 22.421875 Enter the gallons used (-1 to end): 10.3 Enter the miles driven: 200 The miles/gallon for this tank was 19.417475 Enter the gallons used (-1 to end): 5 Enter the miles driven: 120 The miles/gallon for this tank was 24.000000 Enter the gallons used (-1 to end): -1 The overall average miles/gallon was 21.601423