what-is-the-standard-enthalpy-change-chemistry-homework-help

Given the standard enthalpy changes for the following two reactions:

(1)N₂(g) + O₂(g)2NO(g)…… Î”H° = 181.8 kJ

(2)N₂(g) + 2O₂(g)N₂O₄(g)……ΔH° = 9.2 kJ

what is the standard enthalpy change for the reaction:

(3)2NO(g) + O₂(g)N₂O₄(g)……ΔH° = ?

 kJ