I know how to solve this but i don’t understand what it means by “what is x if g(x) is 150”??

Step-by-step explanation:

The rule is 5x - 15

g(x) = 150 which is the same thing as saying

y = 5x - 15

y = 150

150 = 5x - 15     Add 15 to both sides

165 = 5x            Divide by 5

35 = x

Remember that g(x) has all the properties of y

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)