The aquarium is 120 cm long, 1/3 of the length and half of the height. Water filled 5/6 of the aquarium.

The aquarium is 120 cm long, 1/3 of the length and half of the height. Water filled 5/6 of the aquarium. Calculate the volume of the unfilled part of the aquarium.

Determine the width of the aquarium, provided that it is 1/3 of its length, equal to 120 cm.
In order to find a part of an integer value, you must divide it by the denominator of the fraction and multiply by its numerator:

120: 3 * 1 = 40 cm.

The height is half the length, therefore:
120: 2 = 60 cm.

Let’s find the volume, according to the formula:
V = a * b * c. Let’s represent all measurements in dm, assuming that 1 dm = 10 cm:

V = 12 * 4 * 6 = 288 dm³.

Let’s calculate the volume of water in the aquarium, if it is filled by 5/6 part:
288: 6 * 5 = 240 dm³.