Please help! Based on Chemistry on writing a balanced equation?

There are two reactions in formation of nitrogen dioxide.

Under the influence of high temperatures of lightning or of combustion, atmospheric nitrogen and atmospheric oxygen react to form nitrogen monoxide.
N₂(g) + O₂(g) → 2NO(g)
At such high temperature, no nitrogen dioxide is formed because nitrogen monoxide is much stable than nitrogen dioxide. Actually, nitrogen dioxide decomposes to nitrogen monoxide and oxygen at such high temperature.

At room temperature, nitrogen monoxide becomes less stable than nitrogen dioxide, and thus nitrogen monoxide will react with atmospheric oxygen to form nitrogen dioxide.
2NO(g) + O₂(g) → 2NO₂(g)

You can combine the above two equations into one single equation as:
N₂(g) + 2O₂(g) → 2NO₂(g)
However, you should know that there are two reactions at different temperatures, but not one single reaction.

N2 + 2 O2 -> 2 NO2