The range is a set of all possible values of y.
The value of |x-8| is always positive or equal to 0, so the value of -|x-8| will always be negative or equal to 0. So, the greatest value of -|x-8| is 0 and the greatest value of -|x-8|+3 is 0+3=3.
The greatest value of y is 3, so the range is \((-\infty,3]\).
