So it's 3 times f prime of x plus 2 times g prime of x. And once you kind of are more fluent with this property, the derivative of the sum of two things is the sum of the derivatives. And the derivative of a scalar times something is the same thing as the scalar times the derivative of that something. You really could have gone straight from here to here pretty quickly. Now why is this interesting? Well, now we can evaluate this function when x is equal to 9. So h prime of 9 is the same thing as 3 times f prime of 9 plus 2 times g prime of 9.