Easy math please help!!
James is making orange juice from concentrated frozen orange juice that he must mix with water. The concentrated juice is in 12 fluid ounce cartons. The ratio of orange juice concentrate to water is 12 fluid ounces to 36 fluid ounces. If James needs 4.5 gallons of orange juice, which is 576 fluid ounces, how many cartons of concentrated orange juice does he need? (Your answer should just be a number.)