 Okay, so this question asks those, are the, or is this pair of molecules, or give the relationship between this pair of molecules it asks? Okay, so the first thing you want to do is turn one of these, so remember you can rotate around sigma bonds, right, you guys remember that? So I would turn one of these to conformations that's the same as the other one, okay, and see if they line up. So in this case, we've got bromine-back hydrogen for methyl group down in the plane, right? So we've got bromine-hydrogen-methyl in this sort of pattern, do you guys see that? Okay, and a counterclockwise pattern. So here we've got the same pattern here, right? So bromine-hydrogen-methyl in a counterclockwise pattern, do you see that? So if we rotate this like that, counterclockwise, we should be able to get it to this form here, okay? So let's just draw that. So I'm going to rotate that, and when I do, it will get it the same here. Do you guys see that? So what I'd like you to do is re-watch the video again, okay? And if you're having trouble, build the two models and turn one with the sigma bond to make it turn to the other one, okay? So now these sides are the same. Now let's look at this side and see if we can do the same thing, because if we can, then they're the same molecule, okay? If we can't, then there's going to be some other relationship between them, okay? So here we've got methyl bromine-hydrogen, right, in a clockwise fashion, methyl bromine-hydrogen. In a clockwise fashion, what do we have here? Methyl-hydrogen bromine, right? Is that the same or backwards? Backwards. But this one is what? The same, right? So what do we have? We have two stereocenters in each of these molecules, one of them is the same and one of them is opposite. So what are they called? What's the relationship between them? It would be if they were mirror images, not superimposable mirror images. What's the other word? You guys got to know this. Diastereomers. Okay, so same, same, different, different. So if one of them is the same and one of them is different, or if some of them are the same and some of them are different, then they're diastereomers. Okay. If they're all different, then they're enantiomers. If they're all the same, what are they? They're the identical molecules. Okay, can I kill it? Any questions on this one? Questions, ladies, over here? Okay, wonderful.