The Newton’s law Nikolas would use to come up with this idea is the
Third law that states:
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
So, in this case, let's name the first Body A which is the skateboard and the second body B which is the compressed carbon dioxide in a fire extinguisher. Then, as shown in the figure below, according to the Third law:
