# How do you solve the system by substitution y = 4x + 12 and y = 2x + 8?

Jan 1, 2016

$x = - 2 , y = 4$

#### Explanation:

$y = 4 x + 12$

$y - 4 x = 12$ ---$\left(1\right)$

$y = 2 x + 8$ ---$\left(2\right)$

Subsitute (2) into (1)

$2 x + 8 - 4 x = 12$

$- 2 x = - 8 + 12$

$- 2 x = 4$

$x = - 2$

Subsitute x=-2 into (2)

$y = 2 \left(- 2\right) + 8$

$y = - 4 + 8$

$y = 4$

$x = - 2 , y = 4$