Ans: (a) $5(m-2n)$ (b) $(m+3n)(m-2n)$ (c) $(m-2n)(m+3n-5)$
-
$\begin{array}{cl}
& 5m-10n \\
= & 5(m-2n)
\end{array}$ -
$\begin{array}{cl}
& m^2+mn-6n^2 \\
= & (m+3n)(m-2n)
\end{array}$ -
$\begin{array}{cl}
& m^2+mn-6n^2-5m+10n \\
= & (m+3n)(m-2n) – 5(m-2n) \\
= & (m-2n)(m+3n-5)
\end{array}$
