please answer 19 and show your work. thank you.

A theme park has partitioned customers into two classes for check-in purposes. Instead of splitting the line into two M/M/1 queues (one for each respective type), they have decided on a layout consisting of one "priority" M/M/1 queue with a capacity of u = 60 customers per hour. The arrival rates have been, on average, di 12 per hour for type-one (priority) customers, and 12 = 36 per hour for (general) type-two customers. 18. Type-one customers go through the system with no interruptions (that is, they are treated as if they were the only ones there and E[L] =p/(1-P) is in familiar form). What is the average time (seconds) a type-one customer spends in the system? 19. Given the interruptions of type-two customers by type-ones, we have to modify the formula reflecting the mean number in the system as follows: P2 E[L] = (1 - P1) (1 - 1 - 2) Considering the above derivation, what is mean number of type-two customers in the M/M/1 priority system