We need to see the second step of the proof, so we know what needs to be justified. It would also be nice to see the list of answer choices. I'll never understand how someone who can't answer the question and has to ask someone else can then go ahead and decide that the person helping him only needs to see parts of the question.
23.4375 or 24.0 is the bacteria count after 6 hours.
For number one you do 15-9 which is 6 and that’s the answer
For number to do 25-18 which is 7 and that’s the answer for that one
Ratio is 1:3.....added = 4
1/4(48) = 48/4 = 12
3/4(48) = 144/4 = 36
the 2 groups will be 12 and 36