Answer :
1 - 2/3 = 1/3. This is the amount of water we want to find out to fill the aquarium.
1/3 = 10.5 divided by 3.
1/3 = 3.5
Answer: 3.5 gallons of water.
1/3 = 10.5 divided by 3.
1/3 = 3.5
Answer: 3.5 gallons of water.