Answer
$5y^{3}$
Work Step by Step
Using the laws of exponents, the given expression, $
\dfrac{15y^{-7}}{3y^{-10}}
$, is equivalent to
\begin{array}{l}\require{cancel}
\dfrac{\cancel{3}\cdot5y^{-7-(-10)}}{\cancel{3}}
\\\\=
5y^{-7+10}
\\\\=
5y^{3}
.\end{array}