# How do you solve by substitution y = 2x + 4 and y = 3x ?

Jun 10, 2015

$x = 4$
$y = 12$

#### Explanation:

$y = 3 x$ is already solved for $y$. Substitute it into the other equation.

$y = 2 x + 4$ =

Substitute $3 x$ for $y$ and solve for $x$.

$3 x = 2 x + 4$ =

$x = 4$

Substitute $4$ for $x$ in the equation $y = 3 x$.

$y = 3 \left(4\right)$ =

$y = 12$

Check by substituting the values for $x$ and $y$ into both equations.

First equation.

$y = 2 x + 4$ =

$12 = 2 \left(4\right) + 4$ =

$12 = 12$ Check.

Second equation.

$y = 3 x$ =

$12 = 3 \left(4\right)$ =

$12 = 12$ Check.