Can you break down the solution for me for this math problem: When Billy was first hired, he was paid at a rate of $10 per hour.  After 2 months, he was given a raise of $0.50 per hour.  On his first anniversary at work, he was given a raise of $1.00 per hour.  Sally just started working at a different business, and her starting salary is $0.50 more per hour than Billy's starting salary was.  If both Billy and Sally work 20 hours, how much more money will Billy earn than Sally, in dollars?