First, graph the three inequalities: x ≥ 5 , y ≤ 10 , 2x - y ≤ 8
Next, look for the 3 intersections (vertices) of the lines: (5, 2) , (5, 10) , (9, 10)
Finally, input the vertex coordinates into P = 4x + 5y and look for the biggest #.
(5, 2): 4(5) + 5(2) = 20 + 10 = 30
(5, 10): 4(5) + 5(10) = 20 + 50 = 70
(9, 10): 4(9) + 5(10) = 36 + 50 = 86
Answer: maximum profit = 86
