Absorption and gas stripping

It is desired to absorb 90% of the acetone in a gas containing 1.0 mol % acetone inair in a countercurrent stage tower. The total inlet gas flow to the tower is 30.0 kg mol/h, and the total inlet pure water flow to be used to absorb the acetone is 90 kg mol H2O/h. The process is to operate isothermally at 300 K and a total pressure of101.3 kPa. The equilibrium relation for the acetone (A) in the gas–liquid is yA = 2.53xA. Determine the number of theoretical stages required for this separation.