Sabrina Jeffries has a very good explanation of how print authors make money (and how much) on her site: http://www.sabrinajeffries.com/big-misunderstanding-about-money.php
Read this along with my own post about money, to learn "what authors really make." I get asked a lot why I write so many books under so many different names--this is why! (well, one of the reasons why). Enjoy!