Answer
$y=3$
Work Step by Step
Recall:
$$a^y=b \longleftrightarrow \log_a{b}=y$$
Let $y=\log_2{8}$.
Use the definition above to obtain:
\begin{align*}
2^y&=8\\
2^y&=2^3
\end{align*}
Use the rule $a^m=b^m \longrightarrow a=b$ to obtain:
$$2^y=2^3 \longrightarrow y=3$$
