ANSWER
(C) y
EXPLANATION
We have two equations:
The first one is
[tex]x + y = z...(1)[/tex]
The second equation is
[tex]y - z = x...(2)[/tex]
Let us make z the subject of this second equation:
[tex] \implies \: -x +y = z...(3)[/tex]
We now add equation (1) and (3) to get:
[tex](-x + x) + (y + y) = z + z[/tex]
We simplify to get:
[tex]0+2y= 2z[/tex]
[tex]2y= 2z[/tex]
Divide throu by 2.
[tex] \frac{2y}{2} = \frac{2z}{2} [/tex]
[tex]y= z[/tex]
[tex] \therefore \: z = y[/tex]
The correct answer is C
