J.R. S. answered 07/12/22
Ph.D. University Professor with 10+ years Tutoring Experience
This has been answered several times in the past. You might want to do a search of Wyzant answers. It could save you a lot of time.
Lead(II) fluoride = PbF2
PbF2(s) <==> Pb2+(aq) + 2F-(aq)
Ksp = [Pb2+][F-]2
3.991x10-8 = (x)(2x)2
3.991x10-8 = 4x3
x3 = 9.978x10-9
x = 2.15x10-3 M = [Pb2+]