# How do you solve 4x + y = 8 and y = 4x using substitution?

Jul 20, 2016

$x = 1 , y = 4$

#### Explanation:

The y values in both equations are the same.
MAke y the subject in each equation.

$y = - 4 x + 8 \text{ and } y = 4 x$

Now, $\text{ "y " " = subst for each } y$

$\therefore - 4 x + 8 = 4 x$

$8 = 8 x$

$x = 1$

If $x = 1$, then $y = 4 \times 1 = 4$