Question 949207
We are given
X +y = 0
X -2y +9 = 0
from the first equation, we have x = -y by subtraction y from both sides of = 
substitute for x in second equation and we get
-y -2y +9 = 0
-3y = -9
subtract 9 from both sides of =
y = 3 and from first equation x = -3
now substitute for x and y in the second equation
-3 -(2*3) +9 = 0
-3 -6 +9 = 0
-9 +9 = 0
0 = 0
our answers for x = -3 and y = 3, check
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