#### Answer

$x=81$

#### Work Step by Step

In exponential form, the given logarithmic equation, $
\log_3 x =4
,$ is equivalent to
\begin{array}{l}\require{cancel}
x=3^4
.\end{array}
Hence, the value of the variable that satisfies the given equation is
\begin{array}{l}\require{cancel}
x=81
.\end{array}