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

Jun 17, 2016

x=4; y=8

#### Explanation:

You can substitute the value of y variable (y=2x) in the first equation:

$x + 2 x = 12$

and symplify:

$3 x = 12$

$x = \frac{12}{3} = 4$

let's put this value in the second equation, so

$y = 2 \left(4\right) = 8$