A certain aquarium holds 20 gallons of water. How many quarts of water does the aquarium hold?

Let's find out what 1 gallon of water is first. 1 gallon is equivalent to 4 quarts. 20 gallon is equivalent to 80 quarts. What we do here is to multiply: 20 gallons • 4 quarts = 80 quarts The answer is 80 quarts.