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

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Answer 1 · 2015-06-04T21:01:22

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

$y = 11 - 2x$

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

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

$= 7x - 33$

Add $33$ to both ends to get:

$7x=28$

Divide both sides by $7$ to get:

$x=4$

Then

$y = 11 - 2x = 11 - (2xx4) = 11 - 8 = 3$

How do you solve by substitution x-3y=-5x-3y=-5 and 2x+y=112x+y=11?