Answer: 72
Explanation:
The least common denominator (LCD) is the smallest multiple of both denominators. Here, we see that is 36.
Multiples of 9: 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99
Multiples of 12: 2, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144