39. If the letters A, B, C, D, E, F represent the numbers 4 to 9 in some order, and
A + C = D
A + D = 2B
C + E = 2F
then what number does F represent?

8 I dont really know

Every 5 minutes the amount of bacteria would double. So five minutes would allow for the bacteria to fill one bottle since you already have one filled then the next five minutes it doubled again and since u have two bottles doubling two would mean you filled the last two bottles