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does anyone know what the addition method is, and how do i solve this?

-x - 7y = 18
4x + 7y = -30

Respuesta :

Crazyformath
-x-7y=18
4x+7y=-30
-----------------
-x=18+7y
x=18-7y
-------------------
4(18-7y)+7y=-30
72-28y+7y=-30
72-21y=-30
21y=72-(-30)
21y=72+30
21y=102
y=102/21=34/7
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Since x=18-7y,
x=18-7(34/7)
x=18-34=-16.
Answer: x=-16, y=34/7. (-16, 34/7). 

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