Can you get this answer

1/128

Step-by-step explanation:

use formula: an = a1 × r ^ n-1

a1 = 4

r = 0.5

n = 10

a10 = 1/128

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)