A volatile organic carbon (VOC) in a water stream is to be stripped out using an air stream in a countercurrent staged stripper. Inlet air is pure, and flowrate is G = 500 lb/hr. Inlet liquid stream has a mass ratio of X = 0.10 and a flowrate of pure water of 500 lb/hr. The desired outlet mass ratio is X = 0.005. Assume that water is non-volatile and air is insoluble. Find the number of equilibrium stages and the outlet gas mass ratio. Equilibrium data can be represented by Y = 1.5 X.