Answer
$$
\tan B=\frac{length \ of \ side\ opposite \ angle\ B}{length \ of \ side\ adjacent\ angle\ B}
.$$
Work Step by Step
Using the definition of tangent, we fill in the blanks with:
$$
\tan B=\frac{length \ of \ side\ opposite \ angle\ B}{length \ of \ side\ adjacent\ angle\ B}
.$$
