To compare 3 gallons and 30 quarts, we need to convert them to a common unit of measurement. Since there are 4 quarts in a gallon, we can convert 3 gallons to quarts as follows:

3 gallons = 3 x 4 quarts = 12 quarts

Now we can compare 12 quarts (3 gallons) to 30 quarts:

12 quarts < 30 quarts

Therefore, 3 gallons (12 quarts) is less than 30 quarts.