Answer
$-\dfrac{3}{17}$
Work Step by Step
Cancelling the common factor between the numerator and the denominator, the given expression, $
\dfrac{9}{-51}
,$ simplifies to
\begin{array}{l}\require{cancel}
\dfrac{\cancel{3}\cdot3}{\cancel{3}\cdot(-17)}
\\\\=
\dfrac{3}{-17}
\\\\=
-\dfrac{3}{17}
\end{array}
