Two reservoirs whose water levels differ by $20m$ are connected with a compound pipeline

consisting of three pipes in series. Pipes of $200mm$ diameter is connected to upper

reservoir and pipe of $300mm$ diameter is connected to lower reservoir. Middle pipe is $150$

$mm$ diameter. All pipes are $100m$ long with friction factor $0\mathrm{.}023,0\mathrm{.}024$ and $0\mathrm{.}025$

respectively. Consider all losses find rate of flow of water and velocity in each pipe.