The key point is that all these substances dissociate into a three-to-one ratio between the ions in solution. For the solution technique, it does not matter which is the three and which is the one. I hope it is obvious that the three and the one would matter if you were asked the concentrations of the two ions.
Here are the substances and their Ksp values:
Ag3AsO4 Ksp = 1.03 x 10¯22 Al(OH)3 Ksp = 3.5 x 10¯24
Once again, the standard problem is to calculate the molar solubility given the Ksp.
However, let's change up a little bit. Go ahead and solve both problems. The solution set-up and answer are in the answer file. Of course, what I'm assuming is you're getting fairly decent on doing these problems by the time you get here.