Well, just the formula for the area of a triangle, base times height times 1 1⁄2. So, or you could say 1 1⁄2 times our base, which is a length of, see, we have a base of three right over here, we go from one to four. So 1 1⁄2 times three times our height, which is one, two, three, four, times four. Well, this is just going to get us six. All right, last but not least, if we are going from four to six of f of x dx, so that's going to be this area right over here. But we have to be careful. Our function is below the x-axis.