Calculate the Molar Concentration of Uncomplexed Zn²⁺(aq) in a Solution $2.9 \times 10 ^ { 9 }$

Calculate the molar concentration of uncomplexed Zn²⁺(aq) in a solution that contains 0.17 M Zn(NH₃) ₄²⁺ and 0.3775 M NH₃ at equilibrium. K_f for Zn(NH₃) ₄²⁺ is $2.9 \times 10 ^ { 9 }$ .

A) $2.9 \times 10 ^ { - 9 }$ M
B) $1.6 \times 10 ^ { - 10 }$ M
C) $3.5 \times 10 ^ { 8 }$ M
D) $4.1 \times 10 ^ { - 10 }$ M
E) $2.7 \times 10 ^ { 0 }$ M