$\color{#FF6800}{ 3 } \left ( \color{#FF6800}{ x } \color{#FF6800}{ - } \color{#FF6800}{ y } \right ) + \left ( a + 2 b \right ) \left ( x - y \right )$
$ $ Organize the expression with the distributive law $ $
$\color{#FF6800}{ 3 } \color{#FF6800}{ x } \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ y } + \left ( a + 2 b \right ) \left ( x - y \right )$
$3 x - 3 y + \left ( \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \left ( \color{#FF6800}{ x } \color{#FF6800}{ - } \color{#FF6800}{ y } \right )$
$ $ Organize the expression with the distributive law $ $
$3 x - 3 y + \left ( \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \color{#FF6800}{ x } + \left ( \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \color{#FF6800}{ y }$
$\color{#FF6800}{ 3 } \color{#FF6800}{ x } \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ y } \color{#FF6800}{ + } \left ( \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \color{#FF6800}{ x } \color{#FF6800}{ + } \left ( \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \color{#FF6800}{ y }$
$ $ Organize the similar terms $ $
$\left ( \color{#FF6800}{ 3 } \color{#FF6800}{ + } \left ( \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \right ) \color{#FF6800}{ x } \color{#FF6800}{ + } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ + } \left ( \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \right ) \color{#FF6800}{ y }$
$\left ( \color{#FF6800}{ 3 } \color{#FF6800}{ + } \left ( \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \right ) \color{#FF6800}{ x } + \left ( - 3 + \left ( - a - 2 b \right ) \right ) y$
$ $ Arrange the constant term $ $
$\left ( \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \color{#FF6800}{ + } \color{#FF6800}{ 3 } \right ) \color{#FF6800}{ x } + \left ( - 3 + \left ( - a - 2 b \right ) \right ) y$
$\left ( a + 2 b + 3 \right ) x + \left ( \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ + } \left ( \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \right ) \right ) \color{#FF6800}{ y }$
$ $ Arrange the constant term $ $
$\left ( a + 2 b + 3 \right ) x + \left ( \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 2 } \color{#FF6800}{ b } \color{#FF6800}{ - } \color{#FF6800}{ 3 } \right ) \color{#FF6800}{ y }$