I read Calculus Made Easy about 15 years after my last math lesson, and had forgotten a lot of the mechanics of algebra. I went through Algebra and Algebra II for Dummies before reading it. They're really concise, very easy to read and absolutely did the job for me.

Calculus Made Easy is an amazing book btw, by far the best introduction and much better than the way I was taught at school as it actually builds your intuition.