The process consists of three steps. In the first step, each tray is loaded with a packaged snack, a container with fruit, and a packet with plastic utensils. This activity requires $2$ minutes per tray. In Step $2,$ trays are shrink$-$wrapped in batches using a machine that requires a setup of $15$ minutes for each batch of $50$ trays. After the setup, it takes $5$ minutes to shrink$-$wrap all trays at once. Finally, the last step is to place each tray in the airplane food cart. In this step, each tray requires $1$ minute of processing. The capacity of each cart is of $28$ food$-$trays. After filling a cart, it takes an average of $7$ minutes to transport the filled cart to the loading truck and setup another empty cart.