In this video, we learn how to evaluate functions. When evaluating functions, you substitute in the variable to the input given. Once you do this, you will rewrite the equation filing in the appropriate spots with the numbers that you are given. After this, you will evaluate the equation with the proper steps in math. Once you have figured out the problem, you can do this in reverse to make sure you have the correct answer. This is a very easy process and it doesn't take that long. Just make sure you follow the proper rules of math and you'll have the equation finished in no time.