Considering going through some MOOC's to brush up on and learn some new math. One thing I'm looking for are books containing tons of problem sets so I can practice (maybe ones with answers in the back). Are textbooks my only option here?
https://www.google.com/search?q="linear+algebra"+problems+si...
https://www.google.com/search?num=50&newwindow=1&q=calculus+...
https://www.google.com/search?num=50&newwindow=1&q=calculus+...
or variations on that theme. There's a ton of stuff out there.
If you want a print book, check the various "Schaums Outlines" books, or books in the "For Dummies" series with "Workbook" in the title (ex, "Calculus Workbook for Dummies", etc.) There's also the "Problem Solvers" books and those "Humongous Book of X" books. For example:
https://www.amazon.com/Schaums-Solved-Problems-Calculus-Outl...
https://www.amazon.com/Humongous-Book-Calculus-Problems/dp/1...
https://www.amazon.com/Calculus-Workbook-Dummies-Mark-Ryan/d...
https://www.amazon.com/Calculus-Problem-Solver-Solvers-Solut...
and so on...