We have a mixture that is \(35.0 \mathrm{~mol} \% \mathrm{n}\)-butane with unknown amounts of propane and n-hexane. We are able to operate a flash drum at \(400.0 \mathrm{kPa}\) and \(70.0^{\circ} \mathrm{C}\) with (\mathrm{x}_{\mathrm{C6}}=0.700\). Find the mole fraction of \(n\)-hexane in the feed, \(\mathrm{z}_{\mathrm{C} 6}\), and the value of V/F.