My quantitative background has never been super strong, so when I started studying economics, I frequently found myself getting lost in the quantitative problems. This book combines what you need to know from all of your various math and economics textbooks through at least the intermediate level. I ended up a aceing my classes, but I couldn't have done it without this book.
The book is exceptionally clear and shows how to work problems step-by-step. No math is introduced without showing how it can be used in economics. It starts off with the very basics, but by the end is going into differential equations, matrices, optimization of two or more variables, and integration. There are a few typos, which I assume have been corrected in the newer editions. Overall, a great text that I highly recommend to anyone struggling with their economics class at the college level or beginning master's level, or if you just need a refresher on these topics.