I have not read it, but have often seen this one recommended:

https://www.amazon.com/How-Prove-Structured-Daniel-Velleman-...

How to Prove It: A Structured Approach by Velleman. New edition came out in 2019. It appears to be aimed at your level, and pricewise isn't too bad.

I couldn't disagree more. I studied Analysis in the Uni, and even in that environment Rudin is pretty bad. For a total newcomer that book will leave you completely helpless. Also, solutions are a must have, without them you are almsot totally lost. In their absence, it is OK to ask on StackExchange or #math on EFnet.

First let's start with a few books to prep you for college-level maths:

* https://www.amazon.com/How-Study-as-Mathematics-Major-ebook/...

* https://www.amazon.com/How-Read-Proofs-Introduction-Mathemat... ; or

* https://www.amazon.com/Numbers-Proofs-Modular-Mathematics-Al... ; or

* https://www.amazon.com/How-Prove-Structured-Daniel-Velleman-... (I believe you can find solutions to the 2nd edition online)

For Single-Variable Analysis

* https://www.amazon.com/Think-About-Analysis-Lara-Alcock/dp/0...

* https://www.amazon.com/How-Why-One-Variable-Calculus/dp/1119...

* https://www.amazon.com/Mathematical-Analysis-Straightforward... (contains solutions to exercises)

* https://www.amazon.com/Understanding-Analysis-Undergraduate-... (there are solutions online for the 2nd edition)

* https://www.amazon.com/Numbers-Functions-Steps-into-Analysis... (this book is a brilliant exercise-guided approach that helps you build up your knowledge step by step + solutions are provided).

Just wanted to say - you've got giant balls! Going back to school after 9 years - I believe is no small decision. I wish you good luck!

I've been toying with this idea for a while, but haven't able to take this step for various 'excuses'(not enough money ~atm).

Would you mind sharing what went through your mind to finalize this?

What factors influenced you(made-your-money? unemployment? ..??)

Have you already finalized your specialization? Has anyone influenced you in choosing your subjects?

finally, What are you doing for math-prep for CS classes?

fwiw- 'how to prove it' -velleman has helped me to some extent. (http://www.amazon.com/How-Prove-Structured-Daniel-Velleman/d...)