The balanced chemical reaction is:
CuCl2 + 2Na → 2NaCl + Cu
We are given the amount of sodium to be used up in the reaction. This will be the starting point for our calculations.
15 g Na ( 1 mol / 22.99 ) ( 1 mol Cul2 / 2 mol Na ) (134.45 g / 1 mol ) = 43.86 g CuCl2 needed to be able to obtain the maximum amount of copper.