3.9.Consider a costbenefittrade-off problem having the following data.

1. Formulate a linear programming model for this problem on a spreadsheet.
2. Use the spreadsheet to check the following solutions: (x₁, x₂) = (7, 7), (7, 8), (8, 7), (8, 8), (8, 9), (9, 8). Which of these solutions are feasible? Which of these feasible solutions has the best value of the objective function?
3. Express the model in algebraic form.
4. Use the graphical method to solve this model.