Question

-9x+y=16
x-y=0

I have to solve by elimination.
Will someone help me please?

Answer 1

-9x+y=16
x-y=0
add the two equations, the y's cancel each other out
-8x=16
divide by -8
x=-2

Answer 2

To do elimination, you combine the two equations by adding
-9x + y = 16
+ x - y = 0
-8x + 0y = 16

Now that there are 0y, we can solve for x:
-8x = 16
divide both sides by -8
x = -2

To solve for y, plug the answer you got for x in to the original equations.

-9x + y = 16
-9(-2) + y = 16
18 + y = 16
y = -2

x - y = 0
-2 - y = 0
y = -2

x = -2 and y = -2