Step 1 :The function is f(x)=-|x-4|
Step 2 :The absolute value of a number is always non-negative, so |x-4| is always greater than or equal to zero
Step 3 :Therefore, -|x-4| is always less than or equal to zero
Step 4 :The range of f(x) is the set of all non-positive real numbers
Step 5 :The domain of a function is the set of all possible input values
Step 6 :Therefore, the domain of f(x) is all real numbers
Step 7 :\(\boxed{\text{All Real Numbers}}\)