Solute A has a partition coefficient of 3 between toluene and water (with 3 times as much in the toluene phase). Suppose that 100 mL of a 0.010 M aqueous solution of A are extracted with toluene. What fraction of A remains in the aqueous phase (a) if one extraction with 500 mL is performed and (b) if five extractions with 100 mL are performed?