Instruction: To write a mathematical model, you need to do the followings: Define the decision variables and parameters (if they are shown by math symbols). %20 Write the objective function and constraints. The objective function and constraints in the mathematical model should be numbered. %60 Explain each line of the mathematical model after the model by referring to its number. %20 To Solve a mathematical model using Excel solver, the following parts should be done: Report each formula you have used in a cell of your spreadsheet model together with its address. For example, G8=SUMPRODUCT(C8F8,011:F11). %20 Report a screenshot of your spreadsheet model that has been solved and the optimal solution can be seen in it. Use meaningful labels in your spreadsheet model. %60 Report the screenshot of the solver window that has been filled out completely. %20 Question 1: 30 marks A company supplies its four retail outlets from its three plants. The shipping cost per shipment from each plant to each retail outlet, demand per month and maximum supply per month are given below: Outlet retailer Plant 1 2 3 4 2 1 8 5 7 2 Max supply per month 30 20 50 2 9 4 4 5 3 1 3 Demand per month 20 10 10 20 Shipment from Plant 2 to Outlet retailer 2 is not possible. The distribution manager now wants to determine the best plan for how many shipments to send from each plant to the respective retail outlets each month to minimize the total shipping cost while satisfying all demands. a. Write the mathematical model. (15 marks) b. Solve it using Excel solver. (15 marks)