Greg Davis, a business major at the University of South Carolina $($USC$),$ has opened Six Points Saco $($SPS$),$ a specialty subs$$taco restaurant, at the rim of the USC campus. SPS has grown in popularity over the first year that it has been in operation, and Greg is trying to perfect the business model before making it into a franchise. He wants to maximize the productivity of his staff, as well as serve customers well in a timely fashion. One area of concern is the drive$-$thru operation during the $11$:$30$ a$.$m$.$ to $12$:$30$ p$.$m$.$ lunch hour.