System $1$ An average of $40$ customers arrive each hour; interarrival times are exponential. Customers must complete two types of service before leaving the system. The first server takes an average of $30$ seconds $($exponentially distributed$)$ to perform type $1$ service. After waiting in line, each customer obtains type $2$ service $($exponentially distributed with a mean of $1$ minute$)$ from a single server. After completing type $2$ service, a customer leaves the system.