Answer
$y^{2}$
Work Step by Step
Using laws of exponents, then,
\begin{array}{l}
\dfrac{y^{11/3}}{(y^5)^{1/3}}
\\\\=
\dfrac{y^{\frac{11}{3}}}{y^{\frac{5}{3}}}
\\\\=
y^{\frac{11}{3}-\frac{5}{3}}
\\\\=
y^{\frac{6}{3}}
\\\\=
y^{2}
.\end{array}