A solution contains $20\mathrm{.}0\%\frac{w}{w}N{a}_{2}S{O}_4,15\mathrm{.}0\%\frac{w}{w}N{a}_{2}C{O}_3,$ with the rest being water. This solution is passed through an evaporator that removes $10\mathrm{.}0\%$ of the original mass and then crystallizes $20\mathrm{.}0\%N{a}_{2}S{O}_4$ and $30\mathrm{.}0\%N{a}_{2}C{O}_3.$ The crystals formed are $N{a}_{2}C{O}_3$ per ten molecules of $H_{2}O$ and $N{a}_{2}S{O}_4$ per ten molecules of $H_{2}O.$ Calculate the composition of the residual solution.