Each of these is a multiple of 12, so, to simplify the problem we just write the multiples: 3, 4, 5. The LCM of these is 3×4×5=60, because 3, 4, 5 have no common factors. Now we simply bring in the 12 and multiply by 60=720.
So the LCM of 36, 48, 60 is 720.