Answer
$x=-1$.
Work Step by Step
We know that by definition then $log_a {y}=x$, then $y=a^x$. Hence if $log_3 {(3^x)}=-1$, then $3^{-1}=\frac{1}{3}=3^x$, therefore because the base is the same on the two sides of the equation, the exponents must be equal too, hence $x=-1$.
