John's Locomotive Works manufactures a model locomotive. It comes in two versions--a standard (S), and a deluxe (D). The standard version locomotive (S) generates $150 profit per unit. The deluxe version locomotive (D) generates $450 profit per unit. One constraint on John's production is labor hours. He only has 40 hours per week of available labor. The standard version requires 8 hours per unit, while the deluxe version requires 4 hours per unit.
John's milling machine is also a constraint. There are only 60 hours a week available for the milling machine. The standard version requires 1 hour per unit, while the deluxe version requires 2 hours per unit.

Assume (S, D >= 0). John's goal is to maximize profit.

Refer to Scenario 3. The constraint equation for Labor is

1S + 2D ? 60

8S + 4D ? 40

8S + 4D ? 40

1S + 2D ? 60