$\begin{cases} \color{#FF6800}{ 0.2 } \color{#FF6800}{ x } - 0.3 y = - 1 \\ 0.4 x - 5 y = 6.8 \end{cases}$
$ $ Calculate the multiplication expression $ $
$\begin{cases} \color{#FF6800}{ \dfrac { \color{#FF6800}{ x } } { \color{#FF6800}{ 5 } } } - 0.3 y = - 1 \\ 0.4 x - 5 y = 6.8 \end{cases}$
$\begin{cases} \dfrac { x } { 5 } \color{#FF6800}{ - } \color{#FF6800}{ 0.3 } \color{#FF6800}{ y } = - 1 \\ 0.4 x - 5 y = 6.8 \end{cases}$
$ $ Calculate the multiplication expression $ $
$\begin{cases} \dfrac { x } { 5 } \color{#FF6800}{ - } \color{#FF6800}{ \dfrac { \color{#FF6800}{ 3 } \color{#FF6800}{ y } } { \color{#FF6800}{ 10 } } } = - 1 \\ 0.4 x - 5 y = 6.8 \end{cases}$
$\begin{cases} \dfrac { x } { 5 } - \dfrac { 3 y } { 10 } = - 1 \\ \color{#FF6800}{ 0.4 } \color{#FF6800}{ x } - 5 y = 6.8 \end{cases}$
$ $ Calculate the multiplication expression $ $
$\begin{cases} \dfrac { x } { 5 } - \dfrac { 3 y } { 10 } = - 1 \\ \color{#FF6800}{ \dfrac { \color{#FF6800}{ 2 } \color{#FF6800}{ x } } { \color{#FF6800}{ 5 } } } - 5 y = 6.8 \end{cases}$
$\begin{cases} \dfrac { x } { 5 } - \dfrac { 3 y } { 10 } = - 1 \\ \dfrac { 2 x } { 5 } - 5 y = \color{#FF6800}{ 6.8 } \end{cases}$
$ $ Convert decimals to fractions $ $
$\begin{cases} \dfrac { x } { 5 } - \dfrac { 3 y } { 10 } = - 1 \\ \dfrac { 2 x } { 5 } - 5 y = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } } \end{cases}$
$\begin{cases} \dfrac { x } { 5 } - \dfrac { 3 y } { 10 } = - 1 \\ \dfrac { 2 x } { 5 } - 5 y = \dfrac { 34 } { 5 } \end{cases}$
$ $ Solve a solution to $ x$
$\begin{cases} \color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 3 } } { \color{#FF6800}{ 2 } } } \color{#FF6800}{ y } \color{#FF6800}{ - } \color{#FF6800}{ 5 } \\ \dfrac { 2 x } { 5 } - 5 y = \dfrac { 34 } { 5 } \end{cases}$
$\begin{cases} \color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 3 } } { \color{#FF6800}{ 2 } } } \color{#FF6800}{ y } \color{#FF6800}{ - } \color{#FF6800}{ 5 } \\ \color{#FF6800}{ \dfrac { \color{#FF6800}{ 2 } \color{#FF6800}{ x } } { \color{#FF6800}{ 5 } } } \color{#FF6800}{ - } \color{#FF6800}{ 5 } \color{#FF6800}{ y } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } } \end{cases}$
$ $ Substitute the given $ x $ value into the equation $ \dfrac { 2 x } { 5 } - 5 y = \dfrac { 34 } { 5 }$
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 2 } \left ( \color{#FF6800}{ \dfrac { \color{#FF6800}{ 3 } } { \color{#FF6800}{ 2 } } } \color{#FF6800}{ y } \color{#FF6800}{ - } \color{#FF6800}{ 5 } \right ) } { \color{#FF6800}{ 5 } } } \color{#FF6800}{ - } \color{#FF6800}{ 5 } \color{#FF6800}{ y } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } }$
$\color{#FF6800}{ \dfrac { \color{#FF6800}{ 2 } \left ( \color{#FF6800}{ \dfrac { \color{#FF6800}{ 3 } } { \color{#FF6800}{ 2 } } } \color{#FF6800}{ y } \color{#FF6800}{ - } \color{#FF6800}{ 5 } \right ) } { \color{#FF6800}{ 5 } } } \color{#FF6800}{ - } \color{#FF6800}{ 5 } \color{#FF6800}{ y } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } }$
$ $ Solve a solution to $ y$
$\color{#FF6800}{ y } = \color{#FF6800}{ - } \color{#FF6800}{ 2 }$
$\color{#FF6800}{ y } = \color{#FF6800}{ - } \color{#FF6800}{ 2 }$
$ $ Substitute the given $ y $ value into the equation $ x = \dfrac { 3 } { 2 } y - 5$
$\color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 3 } } { \color{#FF6800}{ 2 } } } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 2 } \right ) \color{#FF6800}{ - } \color{#FF6800}{ 5 }$
$x = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 3 } } { \color{#FF6800}{ 2 } } } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 2 } \right ) - 5$
$ $ Calculate the product of rational numbers $ $
$x = \color{#FF6800}{ - } \color{#FF6800}{ 3 } - 5$
$x = \color{#FF6800}{ - } \color{#FF6800}{ 3 } \color{#FF6800}{ - } \color{#FF6800}{ 5 }$
$ $ Find the sum of the negative numbers $ $
$x = \color{#FF6800}{ - } \color{#FF6800}{ 8 }$
$\color{#FF6800}{ x } = \color{#FF6800}{ - } \color{#FF6800}{ 8 }$
$ $ The possible solutions are as follows $ $
$\color{#FF6800}{ x } = \color{#FF6800}{ - } \color{#FF6800}{ 8 } , \color{#FF6800}{ y } = \color{#FF6800}{ - } \color{#FF6800}{ 2 }$
$\color{#FF6800}{ x } = \color{#FF6800}{ - } \color{#FF6800}{ 8 } , \color{#FF6800}{ y } = \color{#FF6800}{ - } \color{#FF6800}{ 2 }$
$ $ Check if it is the solution to the system of equations $ $
$\begin{cases} \color{#FF6800}{ 0.2 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 8 } \right ) \color{#FF6800}{ - } \color{#FF6800}{ 0.3 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 2 } \right ) = \color{#FF6800}{ - } \color{#FF6800}{ 1 } \\ \color{#FF6800}{ 0.4 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 8 } \right ) \color{#FF6800}{ - } \color{#FF6800}{ 5 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 2 } \right ) = \color{#FF6800}{ 6.8 } \end{cases}$
$\begin{cases} \color{#FF6800}{ 0.2 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 8 } \right ) \color{#FF6800}{ - } \color{#FF6800}{ 0.3 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 2 } \right ) = \color{#FF6800}{ - } \color{#FF6800}{ 1 } \\ \color{#FF6800}{ 0.4 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 8 } \right ) \color{#FF6800}{ - } \color{#FF6800}{ 5 } \color{#FF6800}{ \times } \left ( \color{#FF6800}{ - } \color{#FF6800}{ 2 } \right ) = \color{#FF6800}{ 6.8 } \end{cases}$
$ $ Simplify the equality $ $
$\begin{cases} \color{#FF6800}{ - } \color{#FF6800}{ 1 } = \color{#FF6800}{ - } \color{#FF6800}{ 1 } \\ \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } } \end{cases}$
$\begin{cases} \color{#FF6800}{ - } \color{#FF6800}{ 1 } = \color{#FF6800}{ - } \color{#FF6800}{ 1 } \\ \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } } = \color{#FF6800}{ \dfrac { \color{#FF6800}{ 34 } } { \color{#FF6800}{ 5 } } } \end{cases}$
$ $ Since it is true in both equations, it is the solution of the system of equations $ $
$\color{#FF6800}{ x } = \color{#FF6800}{ - } \color{#FF6800}{ 8 } , \color{#FF6800}{ y } = \color{#FF6800}{ - } \color{#FF6800}{ 2 }$