When reaction 1) and 2) below are added together, the result is reaction 3).1) h2o(l) + hno2(aq) ⇌ h3o+(aq) + no2‒(aq) k1 = 4.50 × 10‒42) h3o+(aq) + oh‒(aq) ⇌ 2 h2o(l) k2 = 1.00 × 10143) hno2(aq) + oh‒(aq) ⇌ no2‒(aq) + h2o(l) k3=? find the equilibrium constant, k3?

Chemical reaction 1: 
H₂O(l) + HNO₂(aq) ⇌ H₃O⁺(aq) + NO₂⁻(aq); K₁ = 4,5·10⁻⁴².
Chemical reaction 2:
H₃O⁺(aq) + OH⁻(aq) ⇌ 2H₂O(l); K₂ = 1,00·10¹⁴.
Chemical reaction 3:
HNO₂(aq) + OH⁻(aq) ⇌ NO₂⁻(aq) + H₂O(l); K₃=?
Chemical reaction 3 is sum of chemical reaction 1 and chemical reaction 2:
K₃ = K₁ · K₂.
K₃ = 4,5·10⁻⁴² · 1,00·10¹⁴.
K₃ = 4,5·10⁻²⁸.