# How do you solve the system of equations y= 3x + 12 and 2x - 2y = - 4?

Jun 20, 2018

Substitution.

#### Explanation:

$y = 3 x + 12 \text{ " " } \left(1\right)$

$2 x - 2 y = - 4$

$- 2 y = - 4 - 2 x$

So

$y = \frac{- 4 - 2 x}{-} 2$

$y = 2 + x \text{ " " } \left(2\right)$

Sub $\left(2\right)$ into $\left(1\right)$

$3 x + 12 = 2 + x$

$2 x = - 10$

$x = - 5$

Sub $x = - 5$ into $\left(1\right)$ (I would normally sub it into a given equation as I may have done a mistake in my new equation)

$y = 3 \left(- 5\right) + 12$

$y = - 3$

Therefore,

$y = - 3 \mathmr{and} x = - 5$