$12-33$ When additional band members arrived to help at the car wash $($see Problem $12-32),$ it was decided that two cars should be washed at a time instead of just the one. Both work crews would work at the same rate.

$($a$)$ What is the average time for cars waiting in the line?

$($b$)$ What is the average number of cars in the line?

$($c$)$ What is the average number of cars in the system?

$($d$)$ What is the average time in the system?