Answer:
x - 4
Explanation:
The quickest way to do this is to Factor and "cancel". (Cancelling is not a mathematical term--it really is dividing)
x^2 - 16 is the difference of two squares. Its super-beneficial to recognize a difference of two squares and its factored form:
(x - 4)(x + 4)
Now you have:
(x - 4 )(x + 4) / x+4
The x+4 term "cancels" and you end up with x-4 as your answer.
You could also do this division problem using long division or synthetic division. You will get the same answer.