A closed inexpansible vessel contains air saturated with water vapour

A closed inexpansible vessel contains air saturated with water vapour at 77 degree Celcius. The total pressure of the vessel is 1007mmHg. Calculate the new pressure if the temperature is reduced to 27 degree celcius. (svp water at 77 degree celcius and 27 degree celcius respectively are 314mmHg and 27mmHg. Treat the air in the vessel as an ideal gas )

4 answers

Work each gas independently.

Pair=kT
so for change of air pressure..
P2/(1007-314)=(273+23)/(273+77)

solve for P2, the partial pressure of air at 23C

then you have the partial pressure of water vapor listed as 27mmHg at the new temp. so the Pressure must be P2+27mmhg

I don't understand

please help me