Arthur is comparing the prices of two car rental companies. company a charges $22 per day and an additional $5 as service charges. company b charges $20 per day and an additional $16 as service charges.

part a: write an equation to represent each company's total charges for renting a car for a certain number of days. for both equations (one for company a and one for company b), define variable used.)

part b: which company would charge less for renting a car for 9 days? justify your answers.

part c: how much money is saved by using the services of company b instead of company a to rent a car for 15 days?