By means of a plate column, acetone is absorbed from its mixture with air in a nonvolatile absorption oil. The entering gas contains 25 mole percent acetone, and the entering oil contains 1.5 mole percent of acetone. Of the acetone in the air 90 percent is to be absorbed, and the concentrated liquor at the bottom of the tower is to contain 8 mole percent acetone. The equilibrium relationship is ye=1.9xe. Plot the operating line and determine the number of ideal stages