please answer c and d

During the campus Spring Fling, the bumper car amusement attraction has a problem of cars becoming disabled and in need of repair. Repali personnel can be hired at the rate of $15 per hour, but they only work as one team. Thus, if one person is hired, he or she works alone; two or three people work together on the same repair. One repairer can fix cars in an average time of 30 minutes. Two repairers take 20 minutes, and three take 15 minutes. While these cars are down, lost income is $30 per hour. Cars tend to break down at the rate of 1.80 per hour. Management is trying to decide how many repair persons to hire, and has asked you for cost data. Q. What is the total hourly cost with one repair person? Note: Round your intermediate calculations and final answer to 2 decimal places. b. What is the total hourly cost with two repair persons? Note: Round your intermediate calculations and final answer to 2 decimal places. Answer is complete but not entirely correct. c. What is the total hourly cost with three repair persons? Note: Round your intermediate calculations and final answer to 2 decimal places