Python help needed:

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 sentinel-controlled-repetition script that prompts the user to input the miles driven and gallons used for each tankful. The script should calculate and display the miles per gallon obtained for each tankful. The miles per gallon obtained for each tankful must be displayed using two decimal places. After processing all input information, the script should calculate and display the combined miles per gallon obtained for all tankfuls (that is, total miles driven divided by total gallons used). The combined miles per gallon obtained for all tankfuls must be displayed using two decimal places.

Output

Enter the gallons used (-1 to stop): 12.8

Enter the miles driven: 287

The miles/gallon for this tank was 22.42

Enter the gallons used (-1 to stop): 10.3

Enter the miles driven: 200

The miles/gallon for this tank was 19.42

Enter the gallons used (-1 to stop): 5

Enter the miles driven: 120

The miles/gallon for this tank was 24.00

Enter the gallons used (-1 to stop): -1

The overall average miles/gallon was 21.60