$100$ moles of feed containing $50$ mol$\%$ n$-$pentane and $50$ mol$\%$ n$-$hexane are evaporated under differential conditions at $1$ atm pressure until $60\%$ is evaporated a$)$ Calculate the composition of the remaining liquid in the tank and the average composition of the total distilled vapor and draw the graph b$)$If the same evaporation process was done by flash distillation, what would be the composition of the distilled vapor and the composition of the remaining liquid? NOTE: The relative volatility of pentane compared to hexane is $3\mathrm{.}15.$

$($Draw the two graph of it $)$