Melissa's Photo Studio offers both individual and group portrait options. The process flow diagram below shows that all customers must first register and then pay at one of fwo cashiers. Then depending on if they want a single or group portrait they go to different rooms. Finally everyone picks up their own finished portrait.

a$.$ How long, on average, does it take to complete the entire process for a group portrait? $38$ minutes $($Enter your response as an integer$)$

b$.$ What single activity is the bottleneck for the entire process, assuming the process receives equal amounts of both groups and individuals? Portrait taken

c$.$ What is the capacity of the bottleneck per hour?

The capacity of the bottleneck for individuals is $4$ customers and the capacity of the bottleneck for groups is $3$ groups. $($Enter your responses as integers.$)$