Calculate the Equilibrium Concentration of Zn²⁺(aq) in a Solution That $\times$

Calculate the equilibrium concentration of Zn²⁺(aq) in a solution that is 0.0125 M Zn(NO₃) ₂ and 0.600 M NH₃.
Given: Zn²⁺(aq) + 4NH₃(aq) Zn(NH₃) ₄²⁺(aq) K_f = 2.9 $\times$ 10⁹.

A) 7.8 $\times$ 10^-12 M
B) 4.7 $\times$ 10^-11 M
C) 1.5 $\times$ 10^-8 M
D) 2.5 $\times$ 10^-9 M
E) 2.9 $\times$ 10⁹ M