$\dfrac { 4 } { \color{#FF6800}{ 5 } } + \dfrac { 7 } { \color{#FF6800}{ 9 } }$
$ $ The smallest common multiple in denominator is $ 45$
$\dfrac { 4 } { \color{#FF6800}{ 5 } } + \dfrac { 7 } { \color{#FF6800}{ 9 } }$
$\dfrac { 4 } { 5 } + \dfrac { 7 } { 9 }$
$ $ Multiply the denominator and the numerator so that the denominator is the smallest common multiple $ $
$\dfrac { 4 \times \color{#FF6800}{ 9 } } { 5 \times \color{#FF6800}{ 9 } } + \dfrac { 7 \times \color{#FF6800}{ 5 } } { 9 \times \color{#FF6800}{ 5 } }$
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 4 } \color{#FF6800}{ \times } \color{#FF6800}{ 9 } } { \color{#FF6800}{ 5 } \color{#FF6800}{ \times } \color{#FF6800}{ 9 } } } \color{#FF6800}{ + } \color{#FF6800}{ \dfrac { \color{#FF6800}{ 7 } \color{#FF6800}{ \times } \color{#FF6800}{ 5 } } { \color{#FF6800}{ 9 } \color{#FF6800}{ \times } \color{#FF6800}{ 5 } } }$
$ $ Organize the expression $ $
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 36 } } { \color{#FF6800}{ 45 } } } \color{#FF6800}{ + } \color{#FF6800}{ \dfrac { \color{#FF6800}{ 35 } } { \color{#FF6800}{ 45 } } }$
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 36 } } { \color{#FF6800}{ 45 } } } \color{#FF6800}{ + } \color{#FF6800}{ \dfrac { \color{#FF6800}{ 35 } } { \color{#FF6800}{ 45 } } }$
$ $ Since the denominator is the same as $ 45 $ , combine the fractions into one $ $
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 36 } \color{#FF6800}{ + } \color{#FF6800}{ 35 } } { \color{#FF6800}{ 45 } } }$
$\dfrac { \color{#FF6800}{ 36 } \color{#FF6800}{ + } \color{#FF6800}{ 35 } } { 45 }$
$ $ Add $ 36 $ and $ 35$
$\dfrac { \color{#FF6800}{ 71 } } { 45 }$