If more airplanes and cars are used (both of which burn fuels) carbon levels will decrease ?

If the question is "would the carbon levels decrease?" then they would not, they would increase.

Explanation: More airplanes and cars would burn fossil fuels, and release more carbon dioxide, increasing carbon levels, not decreasing them.

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle