Problem 1: a) Explain how a maximum flow problem for a network with several sources and sinks can be transformed into an equivalent (will give an answer to the original problem) maximum flow problem with a single source and a single sink.

b) Suppose that in addition to the usual constraints a flow network has capacity constraints on the flow that can go through each intermediate vertex. Explain how a maximum flow problem for such a network can be transformed into an equivalent (will give an answer to the original problem) maximum flow problem. Please help with both parts of the question