Murphree tray efficiency problem (Ethanol distillation using Emv)

An ethanol-water mix containing 20 mol% ethanol is to be separated in multiple steps. Flow that is coming out of the column is containing 60 mol% ethanol and through the bottom flow of 2 mol% ethanol is coming out. Reflux ratio is 2. Murphree efficiency based on the vapour is 75%. What is the number of equilibrium stages needed? Feed is supplied as natural liquid (q=1.0).