# How do you solve 3x + y = 1 and x – y = 3?

May 3, 2016

$x = 1 , y = - 2$

#### Explanation:

If you add the two equations together you can get an equation in just one variable.
$3 x + y = 1$
$x - y = 3$

$\therefore 4 x = 4$
$x = 1$

Substituting this back into the second equation gives
$1 - y = 3$
$\therefore y = - 2$