Question

Y = 7x + 9
2y + 2x = -18

Answer 1

x=-9/4, y=-27/4. (-9/4, -27/4).

Explanation:

y=7x+9

2y+2x=-18

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simplify 2y+2x=-18 into y+x=-9

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7x+9+x=-9

8x+9=-9

8x=-9-9

8x=-18

x=-18/8

simplify

x=-9/4

y=7(-9/4)+9=-63/4+9=-27/4

Answer 2

Explanation:

Just multiply the first equation by -1 and then add them together to find x. Should look something like

-2x - y = -7

5x + y = 9

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3x + 0 = 2

x = 2/3

Now back substitute using either equation to find y. I'll use the first:

2(2/3) + y = 7

4/3 + y = 7

y = 7 - 4/3 = 21/3 - 4/3 = 17/3

Answer:

x=2/3

y=17/3