If the grasshoppers in a certain area receive 500 million joules of chemical energy from the plants they eat in one day, what is a reasonable estimate of the amount of chemical energy the frogs in the same area will get from their food ?

50 million joules.

Explanation:

In a food chain, as the trophic level rises, the energy consumed decreases. As a result, each trophic level can only consume 10% of the energy of the previous trophic level.

With that, we can arrive at the following reasoning: The locusts are in a trophic level below the toads, which means that the toads feed on the locusts and will only consume 10% of the energy that the locusts consumed from a vegetable. If a grasshopper consumed 500 million joules, frogs will only receive 10% of that. We can find out the value of energy consumed by frogs in the following calculation:

500 million joules = 100%

X million joules = 10%

X = (500 million * 10) / 100

X = 50 million joules.

i think its the first one