Based on the reactions:

1. 2NO2 (g)N2O4 (g) H1 = - 57.2 kJ
2. 2NO(g) + O2 (g)2NO2 (g) H2 = -114.1 kJ
Use Hess's law to calculate H for:

2NO(g) + O2 (g)N2O4 (g)