Translate to an algebraic expression. alex had x dollars before spending $16.50 for a book. how much did he have after the purchase?

Hector and alex traded video games. alex gave hector one fourth of his video games in exchange for 6 video games. then he sold 3 video games and gave 2 video games to his brother. alex ended up with 16 video games. how many video games did alex have when he started?