How do you solve 3x - 4y = -30 and 7x + 4y = 10?

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Answer 1 · 2016-01-13T13:02:03

The solution for the system of equations is
$color(blue)(x=-2, y=6$

$3x-color(blue)(4y)=-30$ .....equation $(1)$
$7x +color(blue)(4y)=10$ ...........equation $(2)$

Solving by elimination

Adding equations $1$ and $2$

$3x-cancelcolor(blue)(4y)=-30$

$7x +cancelcolor(blue)(4y)=10$

$10x = -20$

$x = -20/10$

$color(blue)(x = -2$

Finding $y$ from equation $1$ :

$3x-4y=-30$

$3 xx (-2) -4y=-30$

$-6 -4y=-30$

$-6 + 30 = 4y$

$24 = 4y$

$color(blue)(y =6$