#### Answer

$(a+5c)(7b+1)$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
Group the terms of the given expression, $
7ab+35bc+a+5c
,$ such that the factored form of the groupings will result to a factor 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}
(7ab+35bc)+(a+5c)
.\end{array}
Factoring the $GCF$ in each group results to
\begin{array}{l}\require{cancel}
7b(a+5c)+1(a+5c)
.\end{array}
Factoring the $GCF=
(a+5c)
$ of the entire expression above results to
\begin{array}{l}\require{cancel}
(a+5c)(7b+1)
.\end{array}