How do you solve by substitution x + 3y = 8 and 2x - y = 9?

Jul 14, 2018

$x = 5 , y = 1$

Explanation:

Solving the first equation for $x$:
$x = 8 - 3 y$
Substituting this ( for $x$)in the second equation

$2 \left(8 - 3 y\right) - y = 9$

expanding

$16 - 6 y - y = 9$

$16 - 7 y = 9$
so

$7 y = 7$ so $y = 1$

and

$x = 8 - 3$

$x = 5$