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

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Answer 1 · 2015-06-04T21:01:22

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

$y = 11 - 2 x$ $y = 11 - 2x$

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

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

$= 7 x - 33$ $= 7x - 33$

Add $33$ $33$ to both ends to get:

$7 x = 28$ $7x=28$

Divide both sides by $7$ $7$ to get:

$x = 4$ $x=4$

Then

$y = 11 - 2 x = 11 - (2 \times 4) = 11 - 8 = 3$ $y = 11 - 2x = 11 - (2xx4) = 11 - 8 = 3$

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