1 mole of CuS${{O}{4}}$ contain 1 mole (1 g atom) of Cu Molar mass of CuS${{O}{4}}$ = 63.5 + 32 + 4 x 16 = 159.5 g ${{mol}^{-1}}$
Thus, Cu that can be obtained from 159.5 g of CuS${{O}{4}}$ = 63.5 g
Cu that can be obtained from 100 g of CuS${{O}{4}}$ =63.5/159.5x100 g=39.81 g