Answer
$4rx(3m^2+mn+10n^2)$
Work Step by Step
$\bf{\text{Solution Outline:}}$
To factor the given expression, $
12m^2rx+4mnrx+40n^2rx
,$ factor the $GCF.$
$\bf{\text{Solution Details:}}$
The $GCF$ of the terms in the given expression is $
4rx
,$ since it is the greatest expression that can divide all the terms evenly (no remainder.) Factoring the $GCF$ results to
\begin{array}{l}\require{cancel}
4rx(3m^2+mn+10n^2)
.\end{array}