Network Flow (Problem 5.20 from text} A company:r has three warehouses that supply four stores with a given product. Each warehouse has 30 units of the product. Stores 1, 2, 3 and 4 require 20, 25, 30 and 35 units of the product, respectively. The per unit shipping costs from each warehouse to each store are given by the following table: Ian-\"nu" ---_ 3 4 3 3 2 Our goal is to determine the least expensive shipping plan to fill the demands at the stores. 1} Draw a network representation of this network. 2) What are the decision variables? 3} What is the objective function? 4} What are the constraints? 5) Using Solver, determine the optimal solution