Pittsburgh and Staunton each have a supply of 1500 units available to ship to the other cities shown in the network diagram. The shipping cost per unit is shown on each arrow. Pittsburgh 3 9 Charleston Richmond 4 7 13 7 3 8 Staunton Roanoke Norfolk 4 4 The required number of units at each of the other cities are as follows: Charleston 350 Roanoke 250 Richmond 950 Norfolk 850 Suffolk 600 Suffolk Note that the demand can be met exactly. What is the cheapest way to transport units and meet the demands? Formulate the situation as an LP problem and set it up in Excel. Use solver to find an optimal solution. Here, please enter the minimum cost: