Answer:
15: 15, 30, 45, 60, 75, 90, 105, 120, 135...etc, 20: 20, 40, 60, 80, 100, 120, 140...etc, 45: 45, 90, 135, 180, 225, 270....etc
Common Multiples: Is 180, Because all of them have a multiple of 180.
Step-by-step explanation:
Hope i helped you. :)
