How to solve exponential equation: (6.76)^-7x/9=13

I've been checking on a few of your questions... but to my knowledge and my studies syllabus, I don't know what's an exponential equation xD but i know how to solve though...
first, please state clearly where is the "bracket", i will just assume it as
(6.76)^(-7x/9) = 13
-7x/9 = log(base6.76) 13
-7x/9 = 1.342186622
x = 1.342186622*9/-7
x = -1.725668514

if you don't know what's a log (logarithm) is, then it is quite not possible to solve this... calculator is very much needed... and if there is no additional bracket, the answer is like this...
6.76^-7x/9 = 13
6.76^-7x = 13*9
-7x = log(base6.76) 117
x = 2.491950232/-7
x = -0.35599289

45,7 - 7x/9 =13
45,7 -13 = - 7x/9
32.7 = -7x/9
32.7 x 9 = -7x
294.3 = -7x
x = - 42