First three common multiples of 15 and 20 would be: 60,120,180
the first three common multiples of 7, 20, and 35 are 140, 280, and 420
15 & 20 have an infinite number of Common Multiples; the first three are 60, 120 and 180.
10, 20, 30 The common multiples of 5 and 10 are multiples of their lowest common multiple. The lcm of 5 and 10, is 10. Thus the first three common multiples are 10, 20, 30.
10, 20, 30
140, 280, 420
140, 280, 420
They are: 20, 40 and 60
10, 20, 30
20, 40, 60
10, 20, 30
20, 40, and 60.