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

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

anonymous · Answer

Well, what do you get when you isolate x in 

-x-y=-8

anonymous · Answer

im not sure

anonymous · Answer

Well.
step 1: add y to both sides
step 2:divide both sides by -1

anonymous · Answer

-x -y= -8
      1      1
-x = -7

anonymous · Answer

Wheres y?

-x-y=-8

add y to both sides

-x=-8-y

divide both sides by -1

x=8+y

anonymous · Answer

x=8+y
/1 /1

anonymous · Answer

We're finished, you substitute 8+y

anonymous · Answer

C