# How do you find the solution of the system of equations y=3x+7 and y=x-9?

##### 1 Answer
May 2, 2015

We can substitute $y = x - 9$ in the first equation to get the value of $x$

We get $x - 9 = 3 x + 7$

Transposing $3 x$ to the left hand side and $- 9$ to the right hand side, we get

$x - 3 x = 7 + 9$

$- 2 x = 16$

Dividing both sides by $- 2$, we get

$\frac{\cancel{- 2} x}{\cancel{- 2}} = \frac{16}{-} 2$

color(green)( x = -8

Substituting $x = - 8$ in the second equation, we get

$y = - 8 - 9$

color(green)( y = -17