By means of a countercurrent stage tower, acetone is absorbed from its mixture with air in a nonvolatile absorption oil. The entering gas flow to the tower is 100 kg mol/h and contains 0.8 mole % acetone and entering oil is acetone free. 97 % of the acetone in the air is to be absorbed, and the concentrated liquor at the bottom of the tower is to contain 1 mole % acetone. The equilibrium relationship is ye=0.6xe. Calculate the number of theoretical stages by using Kremser analytical equations.