The equation is pretty straightforward. Basically, if 10^13 bacteria multiplies in 100 hours. We seek to know how many bacteria multiply per hour.
So if 10^13 bacteria mulitply in 100 hours
Then X bacteria multiply in an hour.
Hence X bacteria * 100 hours = 10 ^13 bacteria * 1 hour.
X = 10 ^13 * 1 / 100= 10^(13-2) 10^11. Basically, 10^11 bacterias multiply in an hour.
