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 and equation to represent each conpanys 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. Part b: which company would charge less for renting a truck for 6 hours? Justify your answer. 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?