There are a whole lot of careers that require a profound knowledge of Algebra, such as accountants, bank officials, architects, advanced programmers and the list goes on and on. Long story short, people from all walks of life may need your books that you don’t really need now and won’t need any time soon if ever.
You can easily sell and get cash for your hardly-ever-used or new Algebra textbooks that are just gathering dust on your bookshelves. The folks out there who are really good at numbers would be more than happy to lay their hands on the books you own but don’t really need. They need it either because your Algebra book is either insanely rare or they just want to save some money on buying a used book because it’ll be beneficial for them in either case.
If you happen to have textbooks on Elementary Algebra, Multilinear Algebra, Algebraic Geometry, Categorical Algebra, Trigonometry or anything in between, you got a great chance to sell your used and unnecessary textbooks that will be of huge use for the people that really need them at this particular time.