Calculate the total pressure and the composition of the vapours $($mole $\%)$ in equilibrium at $60C$ with a well agitated mixture containing $870kgH{H}_{2}O,509kg$ NaCl $($all dissolved$)$ and $750kg$ benzene. Assume that the NaCl and water are both totally insoluble in benzene.

Vapour pressure data at $60C.$

$P^{**}$ benzene $=390mmHg$

$P^{**}$ water $=160mmHg$