# How do you solve by substitution x-3y=-5 and 2x+y=11?

Jun 4, 2015

First subtract $2 x$ from both sides of the second equation to get:

$y = 11 - 2 x$

Substitute this express for $y$ into the first equation to get:

$- 5 = x - 3 y = x - 3 \left(11 - 2 x\right) = x - 33 + 6 x$

$= 7 x - 33$

Add $33$ to both ends to get:

$7 x = 28$

Divide both sides by $7$ to get:

$x = 4$

Then

$y = 11 - 2 x = 11 - \left(2 \times 4\right) = 11 - 8 = 3$