9. LCM of 9, 12, and 15 is 180
12. LCM of 15, 18, and 30 is 90
15. LCM of 40 and 1 is 40
16: factors of 24 : 1,2,3,4,6,8,12, and 24
17: factors of 63 : 1, 2, 4, 8, 16, 32 and 64.
18: factors of 50 : 1, 2, 5, 10, 25, and 50
19: LCM of : 3 , 2 , 7 is 42
20: LCM of : 15 , 2 is 30
21: LCM of : 45, 30 is 90