Gold forms a substitutional solid solution with silver. Calculate the number of gold atoms per cubic centimeter (in atoms/cm^3) for asilver-gold alloy that contains 18.9 wt% Au and 81.1 wt% Ag. The densities of pure gold and silver are 19.32 and 10.49g/cm3, respectively, and their respective atomic weights are 196.97 and 107.87 g/mol.