For the following transportation, problem find the optimal solution using manual solutions ONLY D1 D2 D3 D4 O1 3 1 7 4 O2 2 6 5 9 O3 8 3 3 2 where Capacity at Origin (O1) is 250 units, at O2 is 350 units and at O3 is 400 units. Demand at final destination D1 is 200 units, at D2 is 300 units, at D3 is 350 units and at D4 is 150 units. Unit costs are shown in the table between pairs