Question 346711
... 4x + 21 > 45 and 4x + 21 < 73


or 4x > 24 and 4x < 52


or x > 6 and x < 13


or 6 < x and x < 13


or 6 < x < 13 &#8592; any number between 6 and 13 (non-inclusive)