Answer
$\dfrac{\sqrt{55y}}{15}$
Work Step by Step
Rationalizing the denominator of $
\sqrt[]{\dfrac{11y}{45}}
$ results to
\begin{array}{l}
\sqrt[]{\dfrac{11y}{9\cdot5}}
\cdot
\sqrt[]{\dfrac{5}{5}}
\\\\=
\sqrt[]{\dfrac{55y}{9\cdot25}}
\\\\=
\dfrac{\sqrt{55y}}{3\cdot5}
\\\\=
\dfrac{\sqrt{55y}}{15}
.\end{array}