Look at it this way:
-- 1/3 of 3(quarts of oil) = 1(quart of oil)
-- 1/3 of 3(days) = 1(day)
-- 1/3 of 3(yards of yarn) = 1(yard of yarn)
-- 1/3 of 3(bags of wool) = 1(bag of wool)
-- 1/3 of 3(dairy cows) = 1(dairy cow)
-- 1/3 of 3(bales of hay) = 1(bale of hay )
-- 1/3 of 3(cups of coffee) = 1(cup of coffee)
-- 1/3 of 3(hours of TV) = 1(hour of TV)
-- 1/3 of 3(cheesburgers) = 1(cheesburger)
-- 1/3 of 3(x's) = 1x