That one's pretty clear. But how does this area in green relate to this area there? And to think about that, we just have to think about what does an integral mean? Remember, what does it represent? We've already thought about these like these really small rectangles. We're taking the sum of an infinitely, or the limit as we get an infinite number of these infinitely thin rectangles. But when we're thinking about Riemann sums, we're thinking about, okay, we have some change in x, and then you multiply it times essentially the height, which is going to be the value of the function at that point.