$2\mathrm{.}69.$ The water$-$supply network shown in below has constant$-$head elevated storage tanks at A and $B,$ with inflows and

withdrawals at $C$ and $D.$ The network is on flat terrain, and the pipeline characteristics are as follows:

If all pipes are made of ductile iron, calculate the $r$ value to be used in the Hardy$-$Cross method for each pipe. Assume

that the flows in all pipes are fully turbulent. $($step by step pleaase over confused$)$