36 and 72
No - common multiples of 4 & 12 up to 100 are... 12, 24, 36, 46, 60, 72, 84 & 96
60 and 42 have no common multiples under 100.
The only common multiples of 6 & 7 up to 100 are 42 & 84.
Since the LCM is 12 then the common multiples are multiples of 12 12, 24, 36, 48
24, 48, 72, 96
Multiples of 20 are 20, 40, 60, 80 and 100. For them to be common, they need to be compared to another set of multiples.
12,24,36,48,60,72,84,96,108,,120,132,144
15,30,45,60,75,90
21,69
96 is the only common multiple of 24 and 32 up to 100.
12,24,36,48,60,72,84,96 That's it.