Answer is: The molar solubility of calcium phosphate is 108s⁵ = Ksp.
Balanced chemical reaction: Ca₃(PO₄)₂(s) → 3Ca²⁺(aq) + 2PO₄³⁻(aq).
[Ca²⁺] =
3s(Ca₃(PO₄)₂) =
3s.
[PO₄³⁻] = 2s.
Ksp = [Ca²⁺]³ · [PO₄³⁻]².
Ksp = (3s)³ · (2s)².
Ksp = 108s⁵.
s = ⁵√(Ksp ÷ 108).
