solve 9log exponent 12 and base 3

I have no idea what that means. Try using

log_9(x) to mean log (base 9) of x

If I try to parse your notation, I'd say

9 log_3(12) = 9 (log_3(3)+log_3(4))
= 9(1+2log_3(2))
= 9 + 18log_3(2)

But somehow I doubt that is what you had in mind.