The answer would be, 20 inches, 12 inches in a foot multiplied by 4 feet equals 48 inches, now take 48 inches and multiply it by 28 inches which equals 1,344, then take 26,880 inches and divide it by 1,344 and your answer would be 20 inches. To check your answer the fourmula for volume for that object is, length x width x hight, so you take 48x28x20 and you get a volume of 26,880 inches. I hope that helped.
