BBC
Bbc: Percentages
You can pick up some valuable percentage pointers on how to work with them. When you finish working your way through the pages, you can take an on-line "Test Bite" and check your understanding.
Help Algebra
Help algebra.com: Percents
Converting percents to and from decimals and fractions is demonstrated in detailed examples. Once the concept is understood, you can use it to solve equations that contain percents.