Answer
$\dfrac{1}{5}$
Work Step by Step
Factoring the expressions and then cancelling the common factor/s between the numerator and the denominator, the given expression, $
\dfrac{5x-15}{25x-75}
,$ simplifies to
\begin{array}{l}\require{cancel}
\dfrac{5(x-3)}{25(x-3)}
\\\\=
\dfrac{5(x-3)}{5\cdot5(x-3)}
\\\\=
\dfrac{\cancel{5(x-3)}}{5\cdot\cancel{5(x-3)}}
\\\\=
\dfrac{1}{5}
.\end{array}
