So this is the first part right here. We just did it. That is the first part of the problem. Now let's try to find f of four and f of negative two. Alright, f of four, well, wherever we see the next, we substitute a four there, it's going to be integral from one to four of f prime of u du plus three. So what is going to be the integral from one to four of f prime of u du? So let's look up here.