Answer
$3$
Work Step by Step
The definition of the logarithmic function says that $y=\log_a{x}$ if and only if $a^y=x$. Also, $a\gt0,a\ne1$ and $x\gt0$.
Hence $\ln{e^3}=\log_{e} {e^3}=y$, then $\left(e\right)^y=e^3$.
We know that $a^b=a^c\longrightarrow b=c$ if $a\ne1,a\ne-1$ (which applies here), hence $y=3$.
