A convenience store has two counters: one for quick food $($such as sandwiches, donuts, and muffins$),$ the other for drinks. Each counter serves its customers completely separately. The Food counter has $3$ employees working independently to process customer orders $($i$.$e$.$ a customer is served by a single employee from start to finish$).$ Each food order often takes an employee $2\mathrm{.}5$ minutes to fill on average.$$ There is another employee working at the Drink counter by herself. It usually takes her $1$ minutes to serve one drink customer. The peak hour of the day is form $78$ AM$,$ when $120$ customers typically arrive in that hour. Among them, $60\%$ are usually for food.$$