Please help me with this problem

A clerk at the local coffee shop takes about 4 minutes to process each order.Her customers typically arrive at a rate of 12 every hour.Her shop is small, and only has room to hold three customers waiting in line.She wants to wait on her customers in 10 minutes or less.Use Table D.5 and Little's Law to answer these questions.

a)Does she have enough room in her shop for the typical waiting line?

b)Is she meeting her service objective?

c)If she adds another clerk to serve coffee, how does this impact the waiting time of the customers, and her customer service objectives?