Answer:
18.2 feet^3 of water
Explanation:
First let's find 80% of the full capacity, which is 24. To do that, multiply 24 x 0.8, which is 19.2.
Now how much space to the fish take up? There are 8 fish, and each one takes up 1.5 cubic INCHES. 8 x 1.5 = 12 cubic inches, but we need cubic feet. Luckily, there are 12 inches in 1 foot so it'll be a clean and simple 1 foot. The "cubic" part only shows that we're measuring volume.
The 80% capacity - fish capacity = how much water is needed. That will be 19.2 - 1 = 18.2
That's it! Hopefully this helped!