> Some people ask how much money I can make from this book. The answer is ZERO. There is not a single penny that goes to my pocket. Why do I do that? Textbooks

> Some people ask how much money I can make from this book. The answer is ZERO. There is not a single penny that goes to my pocket. Why do I do that? Textbooks today are just ridiculously expensive. [...] Education should be accessible to as many people as possible, especially to those underpreviledged families. B r a v o ! A free, quality education is the foundation for social progress and economic prosperity.