Question 412030
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Hi
Solve using the multiplication principle first.  Then add.
-x-y=8 equation (1)
2x-y=-1 equation (2) 

-2x-2y=16 |multiplying 1st Eq thru by 2 and then adding to eliminate x
 2x-y =-1 
  -3y = 15
    y = -5  and 
2x = y-1 = -6;
    x = -3

CHECKING our Answer***
 3 + 5 = 8   |this checks...  -(-3) -(-5) = 3 + 5 = 8
 -6+5 = -1