What is the rate of change of the area, a of t, so our area's going to be a function of t, what is the rate of change of the area of the triangle at that instant? And so what we're going to do in this exercise, instead of going straight and trying to solve it, what we need to do here is to identify the various units of different expressions, and then try to think about what information is given and what's not, and then that will actually equip us to actually solve this rate of change problem. So let's just do this first part. Let's match each expression with its units, and like always, pause the video and see if you can do it on your own. All right, so the first one is b prime of t. So this is the rate of change of which the base is changing with respect to time. So if we think about it, b of t, that is the base, that is going to be in meters. So this is going to be in meters.