How do you solve x+y = 4 and y=x+4?

Aug 3, 2015

The solution for the system of equations is
color(blue)(x=0,y=4

Explanation:

$x + y = 4$
x=color(blue)(4-y....equation $\left(1\right)$

$y = x + 4$.....equation $\left(2\right)$

Solving by substitution:

Substituting equation $1$ in equation $2$ to find $y$
$y = x + 4$
$y = 4 - y + 4$
$2 y = 8$
color(blue)(y=4

Substitute $y$ in equation $1$ to find $x$
$x = 4 - y$
$x = 4 - 4$
color(blue)(x=0