Amby Duncan-Carr
Amby's Math Instruction: Using the Proportion Method to Solve Percent Problems
Learn to use the Proportion Method to calculate percentage problems, then practice your skill at the bottom of the page. Extra practice is provided for solving problems with percents. The site allows you to check your answer after...
National Council of Teachers of Mathematics
The Math Forum: Markdown Savings
This site from the Drexel University contains problems for practicing using percents, using a mock sale as the motif. A link takes you to a model solution.