# How do you solve by substitution y=-4x+8 and y=x+7?

Mar 26, 2018

$x = \frac{1}{5}$

#### Explanation:

You have 2 expressions for y. $y = - 4 x + 8 \mathmr{and} y = x + 7$.

The second expression tells us that y is equal to $x + 7$. Let's substitute $x + 7$ for the y in the first expression. That will give us

$x + 7 = - 4 x + 8$

And now, let's simplify.

$x + 4 x = 8 - 7$

$5 x = 1$

Therefore, $x = \frac{1}{5}$.

I hope this helps,
Steve