Is there a book on proofs with solutions? I am a biochemistry graduate student who works on cancer. I am interested in learning proofs as a personal interest. I use math as a tool, but would like to start building a deeper understanding on my own. I am not taking any course. Hence, I am looking for a book with theory, exercise, and solution manual, in case I am stuck. I find this forum extremely helpful, but I would still like to have a reference. Most books that I have started looking to buy do not have a solution manual. Can anyone recommend an author? Sorry for this general question. Thank you! 
EDIT:
I watched the movie Good Will Hunting, so I feel confident! lol I

Well, there are lots and lots of books with solutions.
An answer to your question depends on which part of mathematics you would like to explore. For instance, a series of great ones about real analysis come from Kaczor & Nowak
