Grass starts with 30,000 kcal of energy. a cheetah would of energy after it ate a zebra that had consumed the grass.

The way the energy transfers work in the trophic level systems is that every step above the previous step receives 10% of its energy .

In this case: If the grass has 30,000 kcal of energy, the zebra would receive about 3,000 kcal of energy. And if the cheetah was to eat the zebra, the cheetah would receive 300 kcal of energy.

So your answer is 300. 

Hi!
The answer is 300 kcal. I hope this helps! :)

2hydrogen and 1 covalent