Easy way is to list multipules of 6 6,12,18,24,30,36,42,48,54 so we can see that A doesn't work because 20 doesn't have 6 as a common factor C works D doesn't work because of the 56
answers are B and C
another way is to factor each notice that 6=2*3 so factor each and see if we can find a 2*3 in each
A. 12=2*2*3, so there is a 6 20=2*2*5, not 6
B. 18=2*3*3, so there is a 6 24=2*2*3*3, so there is a 6 works
C. 30=2*3*5, there is a 6 54=2*3*3*3, there is a 6 works
D. 42=2*3*7, there is a 6 56=2*2*2*7, there isn't a 6 nope
Step-by-step explanation: 5200 - 4000 = 1200. 1200 divided by four hours is 300. So 300 bacteria grow per hour. Then you multiply 300 by 11 hours and get 3300 bacteria plus the starting 4000 and your final number is 7300