Percentage of an alloy?

you have a piece of gold jewelry weighing 9.35 g. its volume is 0.654 cm3. ume that the metal is an alloy of gold and silver, which have densities of 19.3 g/cm3 and 10.5 g/cm3, respectively. also ume that there is no change in volume when the pure metals are mixed. calculate the percentage of gold (by m) in the alloy.