SOLUTION: the problem is y=2x+9 y=7x+8 i subtracted 2x from the first equation to get y-2x=9 and subtracted 7x from the second to get y-7x=8 i then used substitution method to get 7

Algebra ->  Expressions-with-variables -> SOLUTION: the problem is y=2x+9 y=7x+8 i subtracted 2x from the first equation to get y-2x=9 and subtracted 7x from the second to get y-7x=8 i then used substitution method to get 7      Log On


   

Question 666134: the problem is
y=2x+9
y=7x+8
i subtracted 2x from the first equation to get y-2x=9 and subtracted 7x from the second to get y-7x=8
i then used substitution method to get 7(2x-y)-y=8 to get 14x-7y-y=8, but i dont know if that is correct to get to the final steps.?
Found 2 solutions by ewatrrr, MathTherapy:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

y=2x+9

y=7x+8

 2x+9 = 7x+8

   1 = 5x

   1/5 = x  and y+=+2%2F5+%2B+9+=+9%262%2F5

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

the problem is
y=2x+9
y=7x+8
i subtracted 2x from the first equation to get y-2x=9 and subtracted 7x from the second to get y-7x=8
i then used substitution method to get 7(2x-y)-y=8 to get 14x-7y-y=8, but i dont know if that is correct to get to the final steps.?

You're making the problem too complicated by doing all of that, which is not necessary, at all.

As you can see, y = 2x + 9, and y = 7x + 8

All you have to do is set the right sides equal to each other since both have already been solved for y

You therefore have: 2x + 9 = 7x + 8

2x - 7x = 8 - 9

- 5x = - 1

x = %28-+1%29%2F-+5, or highlight_green%281%2F5%29

Substituting this value for x in either equation to determine the value for y, and you're all done!!

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