SOLUTION: -4x-y=-21 x-2y=12 Solve by substitution

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Question 940173: -4x-y=-21
x-2y=12
Solve by substitution
Answer by MathLover1(20849) About Me  (Show Source):
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-4x-y=-21....eq.1
x-2y=12+.....eq.2
---------------------
Solve by substitution
x-2y=12+.....eq.2...solve for x
x=2y%2B12+...substitute in eq.1

-4%282y%2B12%29-y=-21....eq.1...solve for y
-8y-48-y=-21
-9y-48=-21...both sides multiply by -1
9y%2B48=21
9y=21-48
9y=-27
y=-27%2F9
highlight%28y=-3%29
go to
x=2y%2B12+...substitute -3 for y
x=2%28-3%29%2B12+
x=-6%2B12+
highlight%28x=6%29+
so, intersection point of these two lines is: (6,-3)

check it on a graph: