Which of the following is an arithmetic sequence? –20, –25, –30, –35, –45, ... –15.6, –12.9, –10.2, –7.5, –4.8, ... 3.1, 6.2, 12.4, 24.8, 49.6, ... 7.2, 3.6, 1.8, 0.9, 0.45, ...

A

Step-by-step explanation:

Because you can't multiply -20 times anything to get -25 you just add -5

you didn't post any answer choices, so its not 100% clear what your teacher is looking for

however, log(15/7) is equivalent to log(15) - log(7)

i'm using the rule log(x/y) = log(x) - log(y)