Which number is a common factor of 27 and 45?

9

Step-by-step explanation:

The biggest common factor number is the GCF number. So the greatest common factor 27 and 45 is 9.

solution given:

1st expression=27=3×3×3

2nd expression=45=5×3×3

here

common factor =3×3=9

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)