please assist

12-12 From historical data, Harry's Car Wash estimates that dirty cars arrive at the rate of 10 per hour all day Saturday. With a crew working the wash line, Harry figures that cars can be cleaned at the rate of one every 5 minutes. One car at a time is cleaned in this example of a single-channel wait. ing line. Assuming Poisson arrivals and exponential service times, find the (a) average number of cars in line. (b) average time a car waits before it is washed, (e) average time a car spends in the service system. (d) utilization rate of the car wash. (e) probability that no cars are in the system