The best method is to let the water evaporate, unless one wants to recover the water. However, case one would distill the mixture. So the water is still distilled and separated in a different container, as the solid salt remains behind in the distilling flask.
The density of the gold is 19.3 grams/cc so each cc weighs 19.3grams. Now we can obtain the volume of gold from the given dimensions ie 4.72x8.21x3.98= 154.23 cc. So for the answer, just multiply the volume or 154.23 x 19.3= 2976.6 grams is the answer.