i think this needs a change of base on the 8

8 = 3^log.3. 8

in general

a^x = b^(log.b. a)(x)

move the term with the negative to the other side so they are all positive

then since you have all the numbers with base 3 you can say the bases are equal therefore the exponents must be equal

and then you can equate the exponents

i get x = 2 - log.3. 8