Solve the LP: Maximize 5x + 4y subject to 2x + y ≤ 20, x + 2y ≤ 20, x,y ≥ 0. What are the optimal values and objective?

• A. Optimal at x = 0, y = 20; objective = 60
• B. Optimal at x = 6, y = 6; objective = 54
• C. Optimal at x = 10, y = 5; objective = 60
• D. Optimal at x = y = 20/3; objective = 60

Answer: (D)