Answer:
125 fish
Explanation:
The Tide Pool has 10 crustaceans and 25 fish. So, simplified, for every 2 crustaceans there are 5 fish. That also means, the amount of crustaceans is 2/5 of the amount of fish.
Deep Blue has 50 crustaceans. That is 2/5 of how many fish are in the tank. Multiply 50 by 5/2 to get the amount of fish.
(50 * 5)/2
250/2
There are 125 fish in the Deep Blue tank.