$2\mathrm{.}117.$ The water$-$supply system shown in Figure $2\mathrm{.}73$ is to be constructed such that water is delivered from a reservoir at $A$ to two communities located at $C$ and $D.$ The pipe lengths, diameters, and demand flow rates are as follows:

$\backslash$table$[[,\backslash$table$[[$Length$],[(km)$