In combustion in air, the amount of nitrogen oxides is tiny. Important for our health, but negligible for streaming, heat amount and so on.
N
2 from air stays essentially untouched. The products are CO
2 (no CO under adequate combustion conditions) and H
20, plus ash that may stay in place or fly with the fumes.
The difficult part is that you generally ignore the detailed composition of the combustible. You don't need too many details neither: usually, only the proportions of C, H O, N are given - and P, S etc if you care about pollutants - plus a heating value. Double-check if the units are moles% or mass%.
The combustion takes O
2 from air and produces CO
2 and H
2O BUT
- It never suppresses all the O2 because CO would begin to appear, so the fire is tuned to avoid it;
- The combustible brings oxygen, don't forget! For instance cellulose is a Cn(H2O)m, where only C takes oxygen to burn;
- The combustible contains humidity, and not little. Double check whether the composition includes it.