To find an equation that is equivalent to \( w = x + y - z \), we can rearrange it to isolate \( z \).
Starting with the original equation:
\[ w = x + y - z \]
We can rearrange it to:
\[ z = x + y - w \]
Thus, the equivalent equation is:
A. \( z = x + y - w \)
So the correct answer is A.