A continuous distillation column is used to produce a $65\%$ ABV rum as distillate product from an $8\%$ ABV wash. Reflux is established through a dephlegmator$/$partial condenser. Energy is saved by using the wash as the cooling fluid in the partial condenser.

The wash is supplied at $100$ kmol$/$h at an initial temperature of $20\backslash$deg C$,$ and leaves the partial condenser at $80\backslash$deg C$.$ The pre$-$heated wash is then heated further up to its bubble point using steam, before being fed into the column. The bottom product contains $0\mathrm{.}2$ mol$\%$ ethanol $(0\mathrm{.}65\%$ ABV$).$

$1.$ Demonstrate that the reflux ratio is approximately $1\mathrm{.}61\mathrm{.}7$

the last equation sent was not very clear, how do i calculate the reflux rate?