An electronics firm produces three types of switching devices. Each type involves a two-step assembly operation. The assembly times are shown in the following table:

Assembly time per Unit (in minutes).	Section #1	Section #2
Model A	2.5	3.0
Model B	1.8	1.6
Model	2.0	2.2

Each workstation has a daily working time of 7.5 hours. Manager Tom wants to obtain the greatest possible profit during the next five working days. Model A yields $8.25 profit per unit Model B yields $7.50 profit per unit Model C yields $7.80 profit per unit. Assume the firm can sell all it produces during this time, but it must fill outstanding orders for 20 units of each model type. Formulate a linear programming model of this problem.