How do you solve $-13x-17y=15$ and $x+y=-3$ ?

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Answer 1 · 2017-02-19T17:23:48

$x=-9$ and $y=6$

$-13x-17y=15$
$x+y=-3$

From the second equation, determine a value for $x$ .

$x+y=-3$

Subtract $y$ from each side.

$x=-3-y$

In the first equation, substitute $x$ with $color(red)((-3-y))$ .

$-13x-17y=15$

$-13color(red)((-3-y))-17y=15$

Open the brackets and simplify. The product of two negatives is a positive.

$39+13y-17y=15$

$39-4y=15$

Subtract $39$ from both sides.

$-4y=-24$

Divide both sides by $-4$ .

$y=6$

in the second equation, substitute $y$ with $color(blue)6$ .

$x+y=-3$

$x+color(blue)6=-3$

Subtract $6$ from both sides.

$x=-9$

How do you solve -13x-17y=15-13x-17y=15 and x+y=-3x+y=-3?