Question

For the following system, if you isolated x in the second equation to use the Substitution Method, what expression would you substitute into the first equation?

2x + y = 9
−x − y = −8

−8 + y

−8 − y

8 + y

8 − y

Answer 1

-x-y=-8
Multiply both sides by -1 then,
x+y=8
Subtract y from both sides then,
x+y-y=8-y
x=8-y

Answer 2

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