Answer:
Greatest possible number of fish = 576 fish.
Explanation:
If there cannot be no more than 18 fish in each tank, then this means that the maximum amount of fish (or greatest amount of fish) is 18 PER tank (since it says "each").
With this knowledge, we can multiply 18 by 32 and we get 576 as our answer.
We are asked for the greatest possible number of fish, so what we have done here is used the information provided (with the maximum for each tank being 18 fish) and multiplied it by 32 to get 576 fish.