Sorry, mistake in my previous post
It should read:
What is the concentration of barium at the moment
more soluble salt starts to precipitate? What does this concentration tell you about less soluble salt anion concentration?
The way it works is that at first less soluble salt precipitates. The more of it precipiates, the less the anion concentration is, the higher the Ba
2+ concentration. At some point [Ba
2+] is high enough to start precipitate the other anion.
Write expressions for both Ksp, check which salt will start to precipiate first.