MacBurger$$s is attempting to determine how many servers $($or lines$)$ should be available during

the breakfast shift. During each hour, an average of $100$ customers arrive at the restaurant. Each

line or server can handle an average of $50$ customers per hour. A server costs $$5$ per hour, and

the cost of a customer waiting in line for $1$ hour is $$20.$ Assuming that an $//$ model is

applicable, determine the number of lines that minimizes the sum of delay and service costs