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Find the ordered pair  that satisfies the system of equations
\(\begin{align*} x+3y &= -4,\\ 3x -7y &= 36. \end{align*}\)

 Jun 28, 2021
 #1
avatar+234 
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Multiply first equation by 3,

\(3x + 9y = -12\)

\(3x -7y = 36\)

Subtract,

\(16y = -48\)

\(y = -3\)

Plug y back into one of the equations,

\(x -9 = -4 \)

\(x = 5\)

So (x, y) = (5, -3)

 Jun 28, 2021
 #2
avatar+785 
+1

$-9x - 27y = 36$

$3x - 7y = 36$

$3x - 7y = -9x - 27y$

$12x = -20y$

$3x = -5y$

$x = - \frac{5}{3} y$

$3x + 9y = -12$

$16y = -48$

$y = -3$

$x = 5$

$(x,y) = (5, -3)$

 Jun 28, 2021

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