In the denominator we're taking the limit as x approaches a. So we can just rewrite this. This we can rewrite as the limit as x approaches a of all this business in orange, f of x minus f of a over x minus a over all the business in green, g of x minus g of a, all of that over x minus a. Now to simplify this, we can multiply the numerator and the denominator by x minus a to get rid of these x minus a. So let's do that. Let's multiply by x minus a over x minus a. So the numerator x minus a and we're dividing by x minus a, those cancel out, and then these two cancel out, and we're left with this thing over here is equal to the limit as x approaches a of, in the numerator we have f of x minus f of a, and in the denominator we have g of x minus g of a. I think you see where this is going.