NO2(g) → 1⁄2N2(g) + O2(g) ΔH1 = -33.9 kJ

Question

NO2(g) → NO(g) + 1⁄2O2(g) ΔH2 = 56.5 kJ

What is ΔH for the reaction 1⁄2N2(g) + 1⁄2O2(g) → NO(g) ?