SOLUTION: 9x+3y= -39 -9x+y = 71 y= 71+9x 9x+3(71+9x)= -39 9x+213+27x = -39 x= ? I know that the coefficient of x is 18 but then I forget how to solve for x

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: 9x+3y= -39 -9x+y = 71 y= 71+9x 9x+3(71+9x)= -39 9x+213+27x = -39 x= ? I know that the coefficient of x is 18 but then I forget how to solve for x       Log On


   

Question 232888: 9x+3y= -39
-9x+y = 71
y= 71+9x
9x+3(71+9x)= -39
9x+213+27x = -39
x= ?
I know that the coefficient of x is 18 but then I forget how to solve for x

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
9x+3y= -39
-9x+y = 71
y= 71+9x
9x+3(71+9x)= -39
9x+213+27x = -39
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36x + 213 = -39
36x = -252
x = -7
-------
y = 71+9x = 71 - 63
y = 8
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Elimination would have been easier for this one, since the coefficients of x are the same.
9x+3y= -39
-9x+y = 71
--------------
0x + 4y = 32
y = 8
----- etc