Answer
$y$
Work Step by Step
RECALL:
The graph of the function $y=f-x)$ involves a reflection across the y-axis of the parent function $y=f(x)$.
The parent function of the given function is $y=|x|$.
Since the function is of the form $y=f(-x)$, then it involves a reflection across the y-axis of the parent function $f(x)=|x|$.
However, since the $f(x)=|x|$ is symmetric with respect to the y-axis, the graph of $f(x)=|-x|$ is the same as the graph of $y=|x|$.
Therefore, the missing expressions in the given statement is:
$y$