Austin is comparing the prices of two truck rental companies. Company A charges $4 per hour and an additional $70 as service charges. Company B charges $5 per hour and an additional $60 as service charges. Part A: Write an equation to represent each company's total charges for renting a truck for a certain number of hours. For both equations (one for Company A and one for Company B), define the variable used. (4 points) Part B: Which company would charge less for renting a truck for 6 hours? Justify your answer. (3 points) Part C: How much money is saved by using the services of Company B instead of Company A to rent a truck for 7 hours? (3 points)