Mark M. answered 08/05/19
Retired math prof. Calc 1, 2 and AP Calculus tutoring experience.
f(4 - x) = f(-x + 4)
Starting with f(x), replace x with -x (this reflects the graph in the y-axis)
Next, replace -x by -x + 4 (this translates the graph 4 units to the left)
So, reflect y = f(x) in the y-axis and then translate the reflected graph 4 units to the left.