The Bijou Theater shows vintage movies. Customers arrive at the theater line at the rate of 100 per hour. The ticket seller averages 30 seconds per customer, which includes placing validation stamps on customers' parking lot receipts and punching their frequent watcher cards. (Because of these added services, many customers don't get in until after the feature has started.)

a. What is the average customer time in the system?

b. What would be the effect on customer time in the system of having a second ticket taker doing nothing but validations and card punching, thereby cutting the average service time to 20 seconds?

c. Would system waiting time be less than you found in(b) if a second window was opened with each server doing all three tasks.

Part C. is the one I need help with the most. Please explain in depth.