$\dfrac { 5 } { 6 } \color{#FF6800}{ \times } \color{#FF6800}{ 15 }$
$ $ Natural numbers can be expressed as fractions with a denominator of 1 $ $
$\dfrac { 5 } { 6 } \color{#FF6800}{ \times } \color{#FF6800}{ \dfrac { \color{#FF6800}{ 15 } } { \color{#FF6800}{ 1 } } }$
$\dfrac { 5 } { \color{#FF6800}{ 6 } } \times \dfrac { \color{#FF6800}{ 15 } } { 1 }$
$ $ Reduce all denominators and numerators that can be reduced $ $
$\dfrac { 5 } { \color{#FF6800}{ 2 } } \times \dfrac { \color{#FF6800}{ 5 } } { 1 }$
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 5 } } { \color{#FF6800}{ 2 } } } \color{#FF6800}{ \times } \color{#FF6800}{ \dfrac { \color{#FF6800}{ 5 } } { \color{#FF6800}{ 1 } } }$
$ $ numerator multiply between numerator, and denominators multiply between denominators $ $
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 5 } \color{#FF6800}{ \times } \color{#FF6800}{ 5 } } { \color{#FF6800}{ 2 } \color{#FF6800}{ \times } \color{#FF6800}{ 1 } } }$
$\dfrac { \color{#FF6800}{ 5 } \color{#FF6800}{ \times } \color{#FF6800}{ 5 } } { 2 \times 1 }$
$ $ Multiply $ 5 $ and $ 5$
$\dfrac { \color{#FF6800}{ 25 } } { 2 \times 1 }$
$\dfrac { 25 } { 2 \color{#FF6800}{ \times } \color{#FF6800}{ 1 } }$
$ $ Multiplying any number by 1 does not change the value $ $
$\dfrac { 25 } { \color{#FF6800}{ 2 } }$