Answer
$\dfrac{5}{x^{a}y^{a-2}}$
Work Step by Step
\text{
Using laws of exponents, the given expression simplifies to
}\\
\begin{align*}
&
\dfrac{25x^{2a+1}y^{a-1}}{5x^{3a+1}y^{2a-3}}
\\\\&=
(25\div5)x^{2a+1-(3a+1)}y^{a-1-(2a-3)}
\\\\&=
5x^{2a+1-3a-1}y^{a-1-2a+3}
\\\\&=
5x^{-a}y^{-a+2}
\\\\&=
\dfrac{5}{x^{a}y^{a-2}}
.\end{align*}
