How do you solve $4x-3y = -15$ and $x + y = 5$ using substitution?

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How do you solve $4x-3y = -15$ and $x + y = 5$ using substitution?

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Answer 1 · 2017-02-11T04:14:40

$x = 0; " "y = 5$

Explanation:

Given:
$4x -3y = -15color(white)(..................)A$
$x +y = 5color(white)(............................)B$

Then, from equation B:
$color(blue)(x = 5 - y)$

Substitute for $x$ in equation A;
$4color(blue)((5 - y)) -3y = -15$
$20 - 4y -3y = -15$
$20 -7y = -15$
$-7y = -15 -20" "$ multiply both sides by $-1$
$7y = 35$
$y = 5$

Substitute the value of $y$ in equation B:
$x +y = 5$
$x +5 =5$
$x = 5 - 5$
$x = 0$

To check, substitute the values into equation A":
$4x -3y = -15$
$4(0) -3(5) = - 15$
$-15 = -15$

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How do you solve $4x-3y = -15$ and $x + y = 5$ using substitution?

1 Answer

Explanation:

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How do you solve 4x-3y = -154x-3y = -15 and x + y = 5 x + y = 5 using substitution?

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How do you solve $4x-3y = -15$ and $x + y = 5$ using substitution?