Arrange the expression in the form of factorization..
$\left ( \color{#FF6800}{ 1 } \color{#FF6800}{ - } \color{#FF6800}{ c } \right ) \left ( 1 - a \right ) \left ( 1 - b \right )$
$ $ Expand the expression $ $
$\left ( \color{#FF6800}{ - } \color{#FF6800}{ c } \color{#FF6800}{ + } \color{#FF6800}{ 1 } \right ) \left ( 1 - a \right ) \left ( 1 - b \right )$
$\left ( \color{#FF6800}{ - } \color{#FF6800}{ c } \color{#FF6800}{ + } \color{#FF6800}{ 1 } \right ) \left ( 1 - a \right ) \left ( 1 - b \right )$
$ $ Bind the expressions with the common factor $ - 1$
$\color{#FF6800}{ - } \left ( \color{#FF6800}{ c } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \left ( 1 - a \right ) \left ( 1 - b \right )$
$- \left ( c - 1 \right ) \left ( \color{#FF6800}{ 1 } \color{#FF6800}{ - } \color{#FF6800}{ a } \right ) \left ( 1 - b \right )$
$ $ Expand the expression $ $
$- \left ( c - 1 \right ) \left ( \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 1 } \right ) \left ( 1 - b \right )$
$- \left ( c - 1 \right ) \left ( \color{#FF6800}{ - } \color{#FF6800}{ a } \color{#FF6800}{ + } \color{#FF6800}{ 1 } \right ) \left ( 1 - b \right )$
$ $ Bind the expressions with the common factor $ - 1$
$- \left ( c - 1 \right ) \times \left ( \color{#FF6800}{ - } \left ( \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \right ) \left ( 1 - b \right )$
$- \left ( c - 1 \right ) \times \left ( - \left ( a - 1 \right ) \right ) \left ( \color{#FF6800}{ 1 } \color{#FF6800}{ - } \color{#FF6800}{ b } \right )$
$ $ Expand the expression $ $
$- \left ( c - 1 \right ) \times \left ( - \left ( a - 1 \right ) \right ) \left ( \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ + } \color{#FF6800}{ 1 } \right )$
$- \left ( c - 1 \right ) \times \left ( - \left ( a - 1 \right ) \right ) \left ( \color{#FF6800}{ - } \color{#FF6800}{ b } \color{#FF6800}{ + } \color{#FF6800}{ 1 } \right )$
$ $ Bind the expressions with the common factor $ - 1$
$- \left ( c - 1 \right ) \times \left ( - \left ( a - 1 \right ) \right ) \times \left ( \color{#FF6800}{ - } \left ( \color{#FF6800}{ b } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \right )$
$\color{#FF6800}{ - } \left ( c - 1 \right ) \times \left ( \color{#FF6800}{ - } \left ( a - 1 \right ) \right ) \times \left ( \color{#FF6800}{ - } \left ( b - 1 \right ) \right )$
$ $ If you multiply negative numbers by odd numbers, move the (-) sign forward $ $
$- \left ( c - 1 \right ) \left ( a - 1 \right ) \left ( b - 1 \right )$
$\color{#FF6800}{ - } \left ( \color{#FF6800}{ c } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \left ( \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \left ( \color{#FF6800}{ b } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right )$
$ $ Sort the factors $ $
$\color{#FF6800}{ - } \left ( \color{#FF6800}{ a } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \left ( \color{#FF6800}{ b } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right ) \left ( \color{#FF6800}{ c } \color{#FF6800}{ - } \color{#FF6800}{ 1 } \right )$