And then you divide both sides by f prime of h of x, and you get our original property there. So now with that out of the way, let's just actually apply this. So we want to evaluate h prime of 14. Or sorry, h prime of negative 14 is going to be equal to one over f prime of h of negative 14. H of negative 14. Now have they given us h of negative 14? Well, they didn't give it to us explicitly, but we have to remember that f and h are inverses of each other.