A win-win for math site webmasters...
You can embed solvers from algebra.com into your webpages. You can continue to display your ads. When your readers click the SOLVE button, they stay on your website.
It is easy, too: browse all solvers, select one, click on "Add to YOUR site", and follow instructions. Put in a one line statement such as this one:
This solver is provided by <A HREF=http://www.algebra.com/>Algebra.Com</A>:<BR> <SCRIPT LANGUAGE=JavaScript SRC=http://www.algebra.com/cgi-bin/embed-solver.mpl?name=substitution></SCRIPT>