Since the concentration of lead(II) and ethandioate are equal we can write:
This is the concentration of lead(II) ions in the saturated solution.
You must always quote the temperature for which Ksp refers. You should be given this with the question.
The Ksp value in this process is the relationship
For each formula unit of lead II oxalate that dissolves you get one lead II ion and one oxalate ion. Let x = these concentrations.
so, after dissolution the ion concentrations are