$5 a - \left ( \color{#FF6800}{ 4 } \color{#FF6800}{ b } \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ + } \left ( \color{#FF6800}{ 8 } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ b } \right ) \right )$
$ $ Get rid of unnecessary parentheses $ $
$5 a - \left ( \color{#FF6800}{ 4 } \color{#FF6800}{ b } \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 8 } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ b } \right )$
$5 a - \left ( \color{#FF6800}{ 4 } \color{#FF6800}{ b } \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 8 } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ b } \right )$
$ $ Organize the similar terms $ $
$5 a - \left ( \left ( \color{#FF6800}{ 4 } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \color{#FF6800}{ b } \color{#FF6800}{ + } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 1 } \color{#FF6800}{ + } \color{#FF6800}{ 8 } \right ) \color{#FF6800}{ a } \right )$
$5 a - \left ( \left ( \color{#FF6800}{ 4 } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \color{#FF6800}{ b } + \left ( - 1 + 8 \right ) a \right )$
$ $ Arrange the constant term $ $
$5 a - \left ( \color{#FF6800}{ 3 } \color{#FF6800}{ b } + \left ( - 1 + 8 \right ) a \right )$
$5 a - \left ( 3 b + \left ( \color{#FF6800}{ - } \color{#FF6800}{ 1 } \color{#FF6800}{ + } \color{#FF6800}{ 8 } \right ) \color{#FF6800}{ a } \right )$
$ $ Arrange the constant term $ $
$5 a - \left ( 3 b + \color{#FF6800}{ 7 } \color{#FF6800}{ a } \right )$
$5 a - \left ( \color{#FF6800}{ 3 } \color{#FF6800}{ b } \color{#FF6800}{ + } \color{#FF6800}{ 7 } \color{#FF6800}{ a } \right )$
$ $ Sort the polynomial expressions in descending order $ $
$5 a - \left ( \color{#FF6800}{ 7 } \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 3 } \color{#FF6800}{ b } \right )$
$5 a \color{#FF6800}{ - } \left ( \color{#FF6800}{ 7 } \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 3 } \color{#FF6800}{ b } \right )$
$ $ Change the symbol of each term in parentheses when there is a (-) symbol in front of parentheses $ $
$5 a \color{#FF6800}{ - } \color{#FF6800}{ 7 } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ b }$
$\color{#FF6800}{ 5 } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 7 } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ b }$
$ $ Organize the similar terms $ $
$\left ( \color{#FF6800}{ 5 } \color{#FF6800}{ - } \color{#FF6800}{ 7 } \right ) \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ b }$
$\left ( \color{#FF6800}{ 5 } \color{#FF6800}{ - } \color{#FF6800}{ 7 } \right ) \color{#FF6800}{ a } - 3 b$
$ $ Arrange the constant term $ $
$\color{#FF6800}{ - } \color{#FF6800}{ 2 } \color{#FF6800}{ a } - 3 b$