So we fist need to convert 3lbs to oz. We can do this by multiplying 3 by 16.
He bought 48 oz of watermelon. Since he ate 36 ounces we just subtract that from the total amount.
48 - 36 = 12
He has 12 ounces left.
3lbs•16ozs=48ozs 48ozs-36ozs=12ozs Harry has 12 ounces of watermelon left.
