Question

If 540 million metric tons of carbon dioxide is released in the air per year and 35% of it is from other fuels, how much carbon dioxide is emitted?

Answer 1

You have said that 540 million metric tons of carbon dioxide is released
in the air per year.

So the answer to the question is: 540 million metric tons of carbon dioxide
are released in the air per year, regardless of the source or sources.