Answer:

Explanation:
Given that,
The dimensions of an aquarium are 61 cm long, 30.5 cm wide, and 30.5 cm high.
The tank is filled to 80% capacity with water.
We need to find the water needed for this tank.
The volume of cuboid is given by :

As it is filled to 80% capacity, so,

So,
of water is needed for this tank.