Hess' Law, calculating ?Hf?

[alex G]

Using Hess' law, calculate ?Hf of NO(g).
4NH3(g)+5O2 => 4NO(g)+6H2O(l), ?H= -1170kJ
4NH3(g)+3O2=> 2N2(g)+6H2O(l), ?H= -1530kJ.

Help, please and thanks.