Aqueous two-phase extraction is used to purify a recombinant hivβ-galactosidase fusion peptide produced in escherichia coli. for optimum separation, 450 kg of a mixture of 19.7% w/w polyethylene glycol (peg) and 17.7% w/w potassium phosphate salt in water is needed. left over from previous pilot-plant trials is 100 kg of a mixture of 20% w/w peg in water, and 150 kg of a mixture of 20% w/w peg and 25% w/w salt in water. also on hand is 200 kg of an aqueous stock solution of 50% w/w peg, 200 kg of an aqueous stock solution of 40% w/w salt, and an unlimited supply of extra water. if all of both leftover mixtures must be used, how much of each stock solution and additional water is required?