Baso4 can dissolve 60g in 250ml saturated solution. According to the relevant public information, baso4 can dissolve 60g in 250ml saturated solution, and the solubility of substance A is 40g if the final valence of positive SO2 in this solution is positive 0. When the saturated solutions of A and B are cooled down to, respectively, they are still saturated solutions with equal solubility, and the relationship between solute mass fraction of the obtained solution is 60g.