A manufacturer produces three models (A, B, and C) of a certain product using iron and copper as raw materials. The following table shows the amount of raw material required in the production of each model and the total amount of raw material available. Requirements per unit (lb) Raw material A B C Availability (lb) Iron 2 3 5 4000 Copper 4 2 7 6000 The following table shows the minimum demand available in the market for each model and the profit per unit contributions. A B C Minimum demand 200 200 150 Profit per unit ($) 30 20 50 How many units of each product should be produced to maximize profit? a) Define the variables. b) State the formulation of the optimization model. c) Solve the problem using Excel Solver, and submit your Excel file in Canvas. State the optimal solution of the problem here.