Answer
$\dfrac{1}{3x+5}$
Work Step by Step
Factoring the expression and then cancelling common factors between the numerator and the denominator, then the given expression, $
\dfrac{9x^2-15x+25}{27x^3+125}
$, simplifies to
\begin{array}{l}\require{cancel}
\dfrac{\cancel{9x^2-15x+25}}{(3x+5)(\cancel{9x^2-15x+25})}
\\\\=
\dfrac{1}{3x+5}
.\end{array}
