Hi, could I please get a step by step explanation for question B?

thank you

Consider a system like the one shown in the picture. Customers arrive at rate to a three-server queuing system (as shown above). Upon being served by station 1, denoted by [Q1, S1], a customer is sent over station 2, denoted as [Q2, S2], with probability q, or sent over to station 3,[Q3,S3], with probability 1 - q. Furthermore, customers done with service at [Q2,S2] leave the system with probability 1r, which means that a customer leaving such station can be sent back to start the process all over again at [Q1, S1] with probability r. a. [12 points] What is the rate at which customers leave station 1, [Q1, S1]? (Hint: call such rate e, and use question 1 above to find it) b. [9 points] What is the rate at which customers leave the system via station 3,[Q3,S3] ? c. 19 points) If it has been known that queue Q1 holds L1 customers on average (time average), what is the average time W1 a customer spends in queue Q1