We have a reaction that can have many possibilities depending on the initial reagents that are not clear.
We have that the initial reactants could be NH2, NH3 or NH4. For each possibility we will have:
[tex]\begin{gathered} 2NH_2+3O_2\rightarrow2NO_2+2H_2O \\ \end{gathered}[/tex][tex]4NH_3+5O_2\rightarrow4NO+6H_2O[/tex][tex]2NH_4+3O_2\rightarrow2NO+4H_2O[/tex]