im assuming you meant 4 1/4 gallons of water. turn the denominator to 16 because 16 cups = 1 gallon and you end up with 4/16. then you multiply 4 by 16 because that is the number of whole gallons and you get 64. Add 4 because thats how many cups were in the fraction and you get 68 cups in 4 1/4 gallons of water :)