The antibiotic streptomycin is extracted from a fermentation broth using an organic solvent, where KD = 40 (g streptomycin/kg extract/g streptomycin/kg raffinate). If the broth contains 1 wt% streptomycin and is fed at 150 kg/min to the solvent extraction unit, what is the required solvent flow rate to recover 80% of the streptomycin?