90, 180, 270.
Since 3 is a factor of 15, the first three common multiples of 3 and 15 are 15, 30, and 45.
15 & 20 have an infinite number of Common Multiples; the first three are 60, 120 and 180.
The two common multiples of three and five are: 15 and 30 ^-^
15, 30, and 45
They are 15, 150, 1500, for example.
15, 30, 45
15, 30, and 45 are.
Since the lowest common multiple of 3 and 5 is 15, the common multiples of 3 and 5 are the multiples of 15: 30, 45, 60, 75, 90, etc...
Multiples of 15 include 15, 30 and 45. For them to be common, they need to be compared to another set of multiples.
135, 270, 405
30 60 90
60, 120, 180