Network flow question

Consider the network below. Assume that we want to find minimum cost flow while satisfying the demands. Nodes 1 and 3 are supply nodes. Nodes 2,4,5 and 6 are demand nodes. a) Find an initial feasible flow. b) Show the capacities and costs on residual network with respect to your answer to part a. c) Check if your solution from part a is optimal (Check optimality conditions. You will not receive any points if you only give the result without the calculations.)