Verified answer

1) 90 ( 90:15= 6, 90:18=5)

2) 48 (48:16= 3, 48:24=2

3) 144 ( 144:72=2, 144:48= 3

4) 2100(2100:350=6, 2100:420=5)

5) 180 ( 180:12=15, :18=10, :36=5)

6) 2520 (:280=9, :360=7,:840=3)