How to calculate the question D, please show the work step!

Bill Youngdahl has been collecting data at the TU student grill. He has found that, between 5:00 P.M. and 7:00 P.M., students arrive at the grill at a rate of 24 per hour (Poisson distributed) and service time takes an average of 2.0 minutes (negative exponential distribution). There is only 1 server, who can work on only 1 order at a time a) The average number in the line = 3.2 customers (round your response to two decimal places). b) The average time in the system = 10 minutes (round your response to one decimal place). c) Suppose that a second server can be added to team up with the first and, in effect, act as one faster server). This would reduce the average service time to 90 seconds. The average time in the system = 3.75 minutes (round your response to two decimal places). d) Suppose a second server is added and the 2 servers act independently, with each taking an average of 2.0 minutes. If a second server is added, the average time a customer spends in the system = 2.38 minutes (round your response to two decimal places)