But the 20 minus two x has to be greater than or equal to zero. You can't cut more cardboard than there is. Or you could say that 20 has to be greater than or equal to two x. Or you could say that 10 is going to be greater than or equal to x, which is another way of saying that x is going to be less than or equal to 10. It's a different shade of yellow. x is going to be less than or equal to 10. So x has got to be between zero and 10.