4060, 8120, 12180.
20, 40, 60...
15 & 20 have an infinite number of Common Multiples; the first three are 60, 120 and 180.
10, 20 and 30.
20, 40, 60
20, 40, 60
20, 40, and 60.
They are: 180, 360 and 540
20, 40 and 60
100, 200, 300
20, 40, 60.
20 30 40
10, 20, 30.