Ka or Kb for salts

[Bradley Bohall 3L]

How do you know if you're supposed to use Ka or Kb for the equilibrium constant in a salt acid-base equilibria problem?

[Dahlia Kirov 3A]

I think you would first have to determine whether the salt is acidic or basic (separating the ionic compound into two individual chemical reactions with water and comparing the strengths of the conjugate acids and bases). Then once you know whether the salt is overall acidic or overall basic, you use Ka or Kb, respectively.