A sample which is having 1.80-g of the mixture is dissolved in water, and an excess of NaOH is added, forming a precipitate of Al(OH)3. A mixture contains only NaCl and Al2(SO4)3. The precipitate is dried, filtered and weighed. The mass of the precipitate is 0.131 g. Determine the mass percent of Al2(SO4)3 in the sample?