Problem C 40% Consider the following minimum-cost flow model: We wish to send twenty units from node 1 to nodes 4 and 5 at minimum cost. The numbers next to the arcs indicate upper bounds for the flow on an arc and the cost per unit of flow. The following solution has been proposed, where the numbers next to the arcs are flows. a) Is the proposed solution a feasible solution? Is it a basic feasible solution? Why? b) How can the proposed solution be modified to constitute a basic feasible solution? c) Determine multipliers on the nodes associated with the basic feasible solution given in b). d) Show that the current basic feasible solution determined in b) is not optimal. e) Find the optimal solution by hand computation