A small backpack manufacturer carriers four different models of backpacks, made of canvas, plastic, nylon, and leather. The bookstore, which will sell the backpacks exclusively, expects to be able to sell between 15 and 40 of each model. The store has agreed to pay $35.50 for each canvas backpack, $39.50 for each plastic backpack, $42.50 for each nylon backpack, and $69.50 for each leather backpack that can be delivered by the end of the week. One worker can work on either canvas or plastic, can complete a backpack in 1.5 hours, and will charge $7.25 per hour to do the work. This worker can work a maximum of 90 hours during the week. Another worker can sew backpacks made of nylon fabric. He can complete a bag in 1.7 hours, will charge $8.25 per hour to work, and can work 42.5 hours in the next week. A third worker has the ability to sew leather. He can complete a backpack in 1.9 hours, will charge $9.25 per hour to work, and can work 80 hours during the next week. The following table provides additional information about each backpack. What is the best combination of backpacks to provide the store to maximize profit? Model Material Required Material Available Cost/ Square Yard Canvas 2.15 200 $4.25 Plastic 2.30 350 $4.50 Nylon 2.00 700 $7.50 Leather 2.50 550 $9.50