Answer
$x\approx 1.242$
Work Step by Step
RECALL:
$$\ln{x}=y \longleftrightarrow e^y=x$$
Use the definition above to obtain:
\begin{align*}
\ln{12}&=2x\\\\
\frac{\ln{12}}{2}&=\frac{2x}{2}\\\\
\frac{\ln{12}}{2}&=x
\end{align*}
Use a scientific calculator to obtain:
$$x\approx 1.242$$