How do you solve $x - y = 9$ $x-y=9$ and $2 x + 2 y = 2$ $2x+2y=2$ ?

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Answer 1 · 2015-11-13T19:30:56

$1 : x - y = 9$ $1: x - y = 9$
$2 : 2 x + 2 y = 2$ $2: 2x + 2y = 2$

Rewrite equation 1:
$x = 9 + y$ $x = 9 + y$

Put $9 + y$ $9+y$ instead of $x$ $x$ in equation 2:
$2 (9 + y) + 2 y = 2$ $2(9+y) + 2y = 2$

Solve like normal:
$18 + 2 y + 2 y = 2$ $18 + 2y + 2y = 2$
#4y = -16

Divide both sides by 4:
$y = - 4$ $y = -4$

Put this value into equation 1:
$x - (- 4) = 9$ $x - (-4) = 9$
$x + 4 = 9$ $x + 4 = 9$
$x = 9 - 4$ $x = 9 - 4$
$x = 5$ $x = 5$

To sum it up; $x = 5$ $x = 5$ and $y = (- 4)$ $y = (-4)$

How do you solve x−y=9x-y=9 and 2x+2y=22x+2y=2?