SOLUTION: Solve the system by substitution. 3x – y = –7 x + y = –9 Help!! I am pulling my hair out! :0) I need help with substitution, I am not understanding. Can someone pl

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Solve the system by substitution.
3x – y = –7
x + y = –9
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Solve either equation for y:
y=3x+7
Substitute that into the OTHER equation to get:
x+(3x+7)=-9
4x=-16
x=-4
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Substitute that into EITHER of the equations to solve for "x":
x+-4=-9
x=-5
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Answer: (-4,-5)
You could check this in the other quation:
3x – y = –7
3(-4)-(-5)=-7
12+5=7
7=7
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Cheers,
Stan H.