(a) If $x=\log _{3}y$, then $y=3^{x}$. For example, $4=\log _{3}81$ is equivalent to $81=3^{4}$.

(b) If $x=\log _{5}y$, then $y=5^{x}$. For example, $$-1=\log _{5}\!\left(\dfrac{1}{5}\right) \hbox{ is equivalent to } \dfrac{1}{5}=5^{-1}$$