Suppose in a transportation network problem, total supply < total demand. Let outflow(J) = sum of flows on the arcs that leave from node J, and inflow(J) = sum of flows on the arcs that enter node j. Finally, let S(J) and D(J) = supply or demand at node j. Further suppose that you do not wish to create a “dummy origin” that has enough additional supply to make up the shortfall. This means that if you use equalities in all of the flow balance equations, you will not be able to achieve a feasible solution. A. Write out the flow balance equation for a supply node: B. Write out the flow balance equation for a demand node: