A solute is to be extracted from an aqueous phase to an organic phase using a continuous extractor. The aqueous feed enters the extractor at a flow rate of 400 L/h and has a solute concentration of 0.5 g/L. The equilibrium relationship is given by C_E=-C_R^2 where CR and CE are the concentrations in the raffinate and extract, respectively. The extraction unit consists of 2 theoretical countercurrent stages. What organic solvent flow rate will be required for 60% recovery of solute?