Check out my books on Amazon (paid link): https://amzn.to/2SiQjlp

You and a stranger encounter an auction house, which has a copy of Game Theory 101: The Complete Textbook available. The rules of the auction are that each player secretly submits a single bid, and those bids must be non-zero and in $10 increments. Whoever submits the highest bid wins the book and pays the price they have bid---hence this is a "first-price" auction. In the event of a tie, a coin flip determines the winner.

It is commonly known that you value the book at $28, and the stranger values the book at $24. What is your optimal bidding strategy?