You are given the following linear programming model in algebraic form, with x1 and x2 as the decision variables:

Minimize Cost = 40x1 + 50x2

Subject to

Constraint 1: 2x1 + 3x2 ( 30

Constraint 2: x1 + x2 ( 12

Constraint 3: 2x1 + x2 ( 20

And

x1 ( 0 x2 ( 0

a. Use the graphical method to solve this model.

b. How does the optimal solution change if the objective function is changed to Cost = 40x1 + 70 x2?

c. How does the optimal solution change if the third functional constraint is changed to 2x1 + x2 ( 15?

d. Now incorporate the original model into a spreadsheet and use Solver to solve this model.

e. Use Excel to do parts b and c?