Best book out there is the
Manhattan GMAT "Word Translations" book. This book covers every possible word problem the GMAT could throw at you and exactly how to translate it into an equation or solve it. It's also only about $20... It also comes with 6 CAT tests, and a bunch of online material. There are 7 other
Manhattan GMAT guides that are good also, I would recommend looking into getting the whole set if you have time (1.5 months or more). If not, pick a few that you think would help you.
PS... make sure you buy the OG12 b/c the
Manhattan books refer to the OG12 for many extra practice problems.
Good luck!
Here is the link to it on Amazon:
https://www.amazon.com/Word-Translations ... 019&sr=1-1