#### Answer

$(m+3)(2-a)$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
Group the terms of the given expression, $
2m+6-am-3a
,$ such that the factored form of the groupings will result to a factor that is common to the entire expression. Then, factor the $GCF$ in each group. Finally, factor the $GCF$ of the entire expression.
$\bf{\text{Solution Details:}}$
Grouping the first and second terms and the third and fourth terms, the given expression is equivalent to
\begin{array}{l}\require{cancel}
(2m+6)-(am+3a)
.\end{array}
Factoring the $GCF$ in each group results to
\begin{array}{l}\require{cancel}
2(m+3)-a(m+3)
.\end{array}
Factoring the $GCF=
(m+3)
$ of the entire expression above results to
\begin{array}{l}\require{cancel}
(m+3)(2-a)
.\end{array}