3. The transportation of the Coastal Company includes three manufacturers, two distribution centers, and four retailers. Manufacturer capacities and shipping costs per unit (in dollars) from each manufacturer to each distribution center are as follows: Retailer demand and shipping costs per unit (in dollars) from each distribution center to each retailer are: Formulate a linear programming model of the problem that minimizes total cost. You should clearly show 1) decision variables, 2) objective function, and 3) constraints. (23pt)