You presented: e^(3x+6) = 8. We want to solve for (3x+6) first, and then for x.
Take the natural log (ln) of both sides. Result:
(3x+6) = ln 8
Subtr. 6 from both sides: 3x = (ln 8) - 6
(ln 8) - 6
Div. both sides by 3: x = -------------
3
Note: I highly recommend using those parentheses! ( )