I sold a book on the Internet for $6.00. I could have sold it at my garage sale for $1.00. I made $5 more on the Internet. What is the profit as a percentage? What is the formula for figuring that per centage?

Question

I sold a book on the Internet for $6.00.  I could have sold it at my garage sale for $1.00.  I made $5 more on the Internet.  What is the profit as a  percentage?  What is the formula for figuring that per centage?