How do you solve the system $8x + 3y= -9$ and $-8x + y = 29$ by elimination?

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Answer 1 · 2015-05-23T12:56:47

Given
$"[1] "8x+3y=-9$
$"[2] "-8x+y = 29$

Add $"[1] + [2]"$
$"[3] "(0)x + 4y = 20$

Which implies
$"[4] "y = 5$

Substituting $"[4] "$ back into $"[1]"$
$"[5] "8x +3(5) = -9$

Gives
$"[6] " x=-3$

So the solution to the given pair of equations is
$(x,y) = (-3,5)$

How do you solve the system 8x + 3y= -98x + 3y= -9 and -8x + y = 29-8x + y = 29 by elimination?