For #3 you first need to know how many inches = a foot and 12 inches = a foot. So The answer would be for feet. The sentence would say, 3 feet. For the teacher you first need to know how many inches is your teacher desk. My teacher's desk is 36 inches. Since 12 inches equal a foot, we can divide 36 by 12 and we would get 3. So for mine my teacher's desk would be equal to 3 foot. The sentence would be: 3 foot. Together the complete sentence is: 3 rulers or 3 feet.
