Since 84 is a multiple of 28, it is automatically the LCM.
The LCM is 84.The LCM is 84.
LCM(28, 6) = 84.
The LCM is: 84
For 84, 49, 28 the LCM is: 588
LCM(21, 28, 42) = 84
LCM(6, 21, 28) = 84.
LCM of 12 and 28 is 84.
The LCM is: 84
84
The answer is 84 21:21,42,63,(84) 28:28,56,(84)
LCM of 12 and 21 is 84, which is also a multiple of 28 so 84 is your answer.