$\color{#FF6800}{ a } \color{#FF6800}{ m } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ m } \color{#FF6800}{ + } \color{#FF6800}{ a } \color{#FF6800}{ n } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ n }$
$ $ Sort the polynomial expressions in descending order $ $
$\color{#FF6800}{ a } \color{#FF6800}{ m } \color{#FF6800}{ + } \color{#FF6800}{ a } \color{#FF6800}{ n } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ m } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ n }$
$\left ( a - b \right ) \left ( m + n \right )$
Arrange the expression in the form of factorization..
$\color{#FF6800}{ a } \color{#FF6800}{ m } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ m } \color{#FF6800}{ + } \color{#FF6800}{ a } \color{#FF6800}{ n } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ n }$
$ $ Expand the expression $ $
$\color{#FF6800}{ a } \color{#FF6800}{ m } \color{#FF6800}{ + } \color{#FF6800}{ a } \color{#FF6800}{ n } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ m } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ n }$
$\color{#FF6800}{ a } \color{#FF6800}{ m } \color{#FF6800}{ + } \color{#FF6800}{ a } \color{#FF6800}{ n } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ m } \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ n }$
$ $ Do factorization $ $
$\left ( \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ b } \right ) \left ( \color{#FF6800}{ m } \color{#FF6800}{ + } \color{#FF6800}{ n } \right )$