$(14$ points$)$ The benzene$-$toluene mixture is separated by a tray distillation tower at normal pressure. There is a full condeaser on the top. The average relative volatility is $2\mathrm{.}47,$ the feed is a saturated vapor with $150$kmol$/$h flowrate, whose composition is $0\mathrm{.}4($molar fraction$).$ The reflux ratio is $4,$ the recovery rate of benzene in the distillate is $0\mathrm{.}97,$ and the recovery rate of toluene in the kettle liquid is $0\mathrm{.}95.$ Calculate the ratio $\frac{R}{R_{\text{M}\text{i}\text{n}}}$