Oh Stink!

So I go to do the Chapter 2 test for my Geology class and realize that I have the wrong edition textbook! The 8th Edition is what I need NOT the 7th Edition that I have. Just what I need, another expensive textbook. OH wait, my brother tells me that I can get it off of e-bay for cheap! Yay! I just hope it comes in quickly so that I can do my reading for the class. See I was using my brother's Geo book from a few years ago and thought that it was the same book. Well it is, just not the right edition. The first chapter was the same, though. If I knew for sure that there wasnt a huge difference I would just keep the one that I've got, but Chapter 2 is missing sooooooo much! So now I wait for my bro to show me how to use e-bay.