Answer
$-\dfrac{5}{2}$
Work Step by Step
Substituting $a=-1$, $b=-2$, and $c=4$, the given expression, $
\dfrac{3|b|-4|c|}{|ac|}
,$ evaluates to
\begin{array}{l}\require{cancel}
\dfrac{3|-2|-4|4|}{|(-1)(4)|}
\\\\=
\dfrac{3(2)-4(4)}{|-4|}
\\\\=
\dfrac{6-16}{4}
\\\\=
\dfrac{-10}{4}
\\\\=
\dfrac{\cancel{2}(-5)}{\cancel{2}(2)}
\\\\=
-\dfrac{5}{2}
.\end{array}
