Consider a piece of gold jewelry that weighs 9.55g and has a volume of 0.660 cm^3 . The jewelry contains only gold and silver, which have densities of 19.3g/cm^3 and 10.5 g/cm^3 , respectively. If the total volume of the jewelry is the sum of the volumes of the gold and silver that it contains, calculate the percentage of gold (by mass) in the jewelry.