[tex]\begin{gathered} w=\frac{x-y}{2}-z \\ \text{add z to both sides of the equation} \\ w+z=\frac{x-y}{2}-z+z \\ w+z=\frac{x-y}{2} \\ \text{cross multiply} \\ 2(w+z)=x-y \\ 2w+2z=x-y \\ \text{subtract x from both sides} \\ 2w+2z-x=x-x-y \\ 2w+2z-x=-y \\ multiply\text{ both sides by -1} \\ x-2w-2z=y \\ y=x-2w-2z \\ y=x-2(w+z) \end{gathered}[/tex]
The answer is D
