What is most likely the amount of energy available at a trophic level of primary consumers if the amount of energy available to secondary consumers in that food web is 200 kilocalories

According to the 10 % law of energy transfer, only 10 % of energy is transferred from lower trophic levels to its higher trophic level. Therefore most of the energy will be present in the produces which comes at a lower trophic level and the least energy will be present in the highest trophic level.

So from primary consumer, only 10 % of energy will be transferred in the second trophic level. Therefore if we want to calculate the energy of the previous trophic level than we have multiply the amount of energy of successive trophic level by 10.

Therefore by multiplying 200*10  we will get the total amount of energy to be 2000 kilocalories. That means that 2000 kilocalories of energy was available at the trophic level of primary consumers.