Normal heptane, $n-\mathrm{C}_{7} \mathrm{H}_{16}$, and normal octane, $n-\mathrm{C}_{8} \mathrm{H}_{18}$, form ideal solutions. At $373 \mathrm{~K}$, normal heptane has a vapor pressure of $106 \mathrm{kPa}$ and normal octane of $47.1 \mathrm{kPa}$.

(a) What would be the composition of a heptane-octane solution that boils at $373 \mathrm{~K}$ under a pressure of $80 \mathrm{kPa}$ ?

(b) What would be the composition of the vapor in equilibrium with the solution that is described in part (a)?