9x = 3 * 3 * x
3x = 3 * x
45 = 3 * 3 * 5
It's like we're making a parts list that has enough parts to make 9x, 3x, or 45. In this case our parts list is 3 * 3 * 5 * x because that has enough parts to make 9x, 3x, or 45.
3 * 3 * 5 * x = 45x
Answer: The least common denominator (LCD) is 45x.