The diagram to the bellow network depicts a system of aqueducts from originate node and then branch to three rivers $($nodes R$1,$ R$2,$ and R$3)$ and terminate at a major city $($End$),$ where the other nodes are junction points in the system.

a$.$ Using dynamic programming, analyse and solve the following network problem in Forward approach?

b$.$ Using dynamic programming, analyse and solve the following network problem in backward approach?