A grass starts with 30,000 MJ of energy. How much energy would a cheetah acquire after it ate a zebra that consumed the grass

The answer is 300 joules of energy.

An energy pyramid is a presentation of the trophic levels in an ecosystem. Energy from the sun is transferred through the ecosystem by passing through various trophic levels. Roughly 10% of the energy is transferred from one trophic level to the next, thus preventing a large number of trophic levels.