Answer
$(5a-2)(2a-1)$
Work Step by Step
Grouping the first and second terms and the third and fourth terms, the given expression is equivalent to
\begin{array}{l}\require{cancel}
10a^2-4a-5a+2
\\\\=
(10a^2-4a)-(5a-2)
.\end{array}
Factoring the $GCF$ in each group results to
\begin{array}{l}\require{cancel}
2a(5a-2)-(5a-2)
.\end{array}
Factoring the $GCF=
(5a-2)
$ of the entire expression above results to
\begin{array}{l}\require{cancel}
(5a-2)(2a-1)
.\end{array}