Calculate the amount of water (in grams) that must be added to (a) 5.00 g of urea $\left(\mathrm{NH}_2\right)_2 \mathrm{CO}$ in the preparation of a 16.2 percent by mass solution, and (b) 26.2 g of $\mathrm{MgCl}_2$ in the preparation of a 1.5 percent by mass solution.