[3.5pt][Partial credit available] Write the LP algebraic formulation for the following transshipment problem. A1 and A2 are supply nodes (with supply amount of 15 each) and L1, L2, and L3 are demand nodes (with demand amount of 10 each). L1) 10 250 550 15 A1 S1 300 500 500 L2 10 600 350 450 650 15 A2 S2 450 L3 10 Define decision variables clearly. For example, if you denote A1 as node 1, S2 as node 3, then the decision variable for the arc connecting A1 and S1 would be X13