5-a) A minimum cost flow problem have both arcs (i, j) and (i, j) for nodes i and j. Transform this problem to a problem in which the network contains either arc (i, j) or arc (i, j), but not both. b) Assume that a minimum cost flow code is such that its input data should not be lij = uij for arc (i, j) (where l is lower bound and u is the capacity of arc (i, j)). How can this arc be eliminated