Rectification

A benzene-toluene feed containing 45 mol% benzene at 101.3 kPa enters an enriching tower at 80 kgmol/h as a saturated vapour. The distillate is to contain 95 mol% benzene. What is the maxinum number of theoritical stages required to perform the separation? If the reflux ratio is set at 3:1. Calculate the kgmol/h distillate D and bottoms W, and their compositions and the number of real plates required, assuming a tray efficiency of 40%