So this is plus 17 right over here. Plus 17. And so my change in y over change in x, change in y over my change in x, for this secant line between when x is equaling three and x is equaling five, is going to be equal to 17 over two. 17 over two, which is equal to 8.5. So the slope of this green line here is 8.5, and that would be our best estimate for the slope of the tangent line when x equals four of the curve y is equal to f of x. And so lucky for us, the people who wrote this question had the exact same logic, and they did it right over there. So you wouldn't have to graph it the way I did.