A natural draft cooling tower is used to remove heat from the cooling water flowing through the condenser of a thermoelectric plant that operates on a Rankine cycle with regeneration. The turbine receives $93$ lbm$/$s of water vapor at $2500$ psia and $1000$F; $18\%$ of this steam is used in a closed$-$type feedwater heater operating at $140$ psia and the remainder is expanded in the turbine to a pressure of $1\mathrm{.}5$ psia and a quality of $97\%.$ The cooling water from the cooling tower enters the condenser at $80$F and leaves it to the tower at $104$F$.$ Atmospheric air enters the tower at a TBS of $73$F and TBH of $64$F and leaves it saturated at $99$F$.$ For the indicated conditions, determine: a$)$ The volumetric flow of the atmospheric air at the entrance to the tower $($CFM$,$ ft$^3/$minute$)$ b$)$ the mass flow of the make$-$up water $($lbm$/$s$)$