#### Answer

$3$

#### Work Step by Step

Using the properties of radicals, the given expression, $
\dfrac{\sqrt{18y}}{\sqrt{2y}}
,$ simplifies to
\begin{array}{l}\require{cancel}
\sqrt{\dfrac{18y}{2y}}
\\\\=
\sqrt{9}
\\\\=
3
\end{array}
* Note that it is assumed that all variables represent positive numbers.