An Internet service provider has three different subscription packages for its Package A: Package B: Package C: For $9.95 per month 10 hours of access are provided. Additional hours are $2.00 per hour For $13.95 per month 20 hours of access are provided. Additional hours are $1.00 per hour For $19.95 per month unlimited access is provided. Write a program that calculates a customer's monthly bill. It should ask the user to enter the letter of the package the customer has purchased (A, B, or C) and the number of hours that were used. It should then display the total charges