Can you help me with this assignment? Thank you in advance

Consider a closed system where multiple concurrent users get service from a CPU and a disk

subsystem. The average number of users in the system is $40.$ The CPU and disk subsystem are

connected by a bus system which only allows $6$ concurrent customers on average to use the disk

subsystem. Other customers are forced to queue at the bus before being admitted. The throughput

of this system is measured to be $10$ customer completions per second. The end$-$to$-$end response

time of a customer is $2$ seconds. The response time of a customer at the CPU is measured to be $1$

second $($overall visits$).$

i$)$ What is the user$$s think time?

ii$)$ What is the average time a customer waits before getting into the disk subsystem?