# Need help with solving 4x-y=9, x-3y=16?

Jun 3, 2018

$x$ is equal to $1$ and $y$ is equal to $- 5$.

#### Explanation:

$\left\{\begin{matrix}4 x - y = 9 \\ x - 3 y = 16\end{matrix}\right.$

Do

$4 x - y = 9$
$\left(x - 3 y\right) \times 4 = 16 \times 4$

So

$\left\{\begin{matrix}4 x - y = 9 \\ 4 x - 12 y = 64\end{matrix}\right.$

Subtract the two equations

$0 x + 11 y = - 55$

$11 y = - 55$

$y = - 5$

Replace $y$ in the first equation

$4 x - y = 9$

$4 x - \left(- 5\right) = 9$

$4 x + 5 = 9$

$4 x = 4$

$x = 1$