$6\mathrm{.}2.$ Flash vaporization of a heptane$-$octane mixture

A liquid mixture containing $50$mol$\%n-$heptane $($A$)$ and $50$mol$\%-$octane $($B$),$ at $303K,$ is to be continuously flash$-$vaporized at a temperature of $350K$ to vaporize $30$mol$\%$ of the feed. What will be the composition of the vapor and liquid and the pressure in the separator if it behaves as an ideal stage?

Answer: $y_D=0\mathrm{.}654$

a Heptane$-$octane mixture

Repeat $6\mathrm{.}3$ calculations for $80$mol$\%$ of the liquid distilled.

Answer yDaw$=0\mathrm{.}573$

Please show all the work, Only need $6\mathrm{.}2$ and $6\mathrm{.}6,$ but posted the rest cause it's needed to answer $6\mathrm{.}6$