I don't know why but I do not see many people on forums/online games using this site. A kid in one of my gen chem classes told me about cramster.com. You can search for your text book and then look up the way to do problems. It's all done/approved by people, who know what they're doing. For math/physics it's really helpful because all of the steps are listed. So far all of my college textbooks have been easy to find
I've used it for one of my classes at college/uni, it's really good at helping you understand the information as opposed to just giving you the answers. Highly recommended for engineers.