A company that manufactures products in two plants ships locally using its own transportation system, but it

Question:

A company that manufactures products in two plants ships locally using its own transportation system, but it has orders that must be sent to customers too far away to be serviced by the local fleet. It therefore contracts with a middle-distance carrier to complete its shipping. The locations of the two manufacturing plants, amounts available at each plant to be shipped per week, locations of the three customers, their weekly requirements, and shipping costs ($ per unit) between each plant and customer are shown in the table at the top of this page.
What is the optimal shipping plan to satisfy the demand at the lowest total shipping cost?