A local Moroccan manufacturer of electrical switches for power stations has just received its licence to be an official ONEE supplier. Part of its plans to manufacture a specific switch, named SW123H, the manufacturer considers 4 potential plants that can manufacture the switch and 3 regional warehouses from where ONEE's demand is fulfilled. The manufac- turer needs to make a decision on: 1) which plant(s) to open and 2) a shipping plan from the plants to the warehouses. When a plant is opened, a fixed cost needs to be paid indepen- dently of how many SW123H switches are produced at the plant. There are also variable unit transportation costs between the plants and the warehouses. All the demand at level of the warehouses needs to be satisfied. Finally, the plants do not have any storage space, so all the switches produced need to be sent to the warehouses. The table below summarizes the problem's parameters. Plant/Warehouse Unit Shipping Costs (USD) Capacity Fixed Cost (USD) 1 2 3 1 55 20 34 122 219975 234 19 46 12 77 4 Demand 35 26 62 149 7230 182 83810 42 149 181009 53 102 110993 101 (a) (3 points Suggested completion time = 3 min) Express the problem's decision vari- ables. (b) (3 points Suggested completion time = 2 min) Express the problem's objective. (c) (8 points Suggested completion time = 6 min) Express the problem's constraints. (d) (6 points - Suggested completion time = 15 min) Take your model to Excel and solve the formulation using Excel's Solver. Report the optimal total cost of the solution ob- tained. (Note: You need to submit your Excel sheet with your answer!) - (e) (2 points Suggested completion time = 1 min) Indicate which plants should be opened as recommended by the optimal solution obtained