Question

I'm really not understanding how to solve this problem and this will be on my final.

What is the solution of the system?
4x - 4y = -40
-4x + 7y = 55

Answer 1

Hint: Add them together

Answer 2

(4x - 4x) + (7y - 4y) = 55 - 40

Answer 3

You can only add the equations together in cases where one of the variables will cancel. This is one of those cases.

Answer 4

So I would get (5,5)

Answer 5

y = x+10

I think.

Answer 6

http://puu.sh/1zSbn

Answer 7

@assaulth3ro911

no bro

Answer 8

@AstralDnB

They're not both positive. One coordinate is positive. The other, negative.

Answer 9

You have to pay attention to signs.

Answer 10

ok. I re-did everything and got (5,-5)

Answer 11

Now you have it backwards

Answer 12

Oh sorry about. Got excited and posted the answer backwards. Thnx for you help.