# How do you solve x + y = 12 and y = 2x using substitution?

Mar 20, 2016

$\left(x , y\right) = \left(4 , 8\right)$

#### Explanation:

color(blue)(x+y=12

color(blue)(y=2x

Substitute the value given for $y$ in the second equation to the first equation

$\rightarrow x + 2 x = 12$

$\rightarrow 3 x = 12$

color(green)(rArrx=12/3=4

Substitute the value of $x$ to the second equation

$\rightarrow y = 2 \left(4\right)$

color(green)(rArry=8

color(indigo)( :.ul bar |x,y=4,8|