helpAn air stream at $35C$ is to be used in a dryer and is first preheated in a steam

heater, where it is heated to $70C.$ The air flow is $2000kg$ mol$/$hour$.$ The steam

enters the heater saturated at $150C,$ is condensed and cooled, and leaves as a

liquid at $140C.$ Determine the amount of steam used in $k\frac{g}{h}$our. $(10$ marks$)$