After a heavy rainstorm, Barbara’s dog left muddy paw prints all over her back patio. She decided to rent an electric pressure washer to clean up the mess. The piecewise function below shows the rental charges for the pressure washer, dependent upon how many hours she rents it. Due to high demand, you cannot rent the washer for more than 24 hours at a time. Barbara’s brother asked to use the washer and agreed to pay Barbara for any additional monies owed. If Barbara used the washer for 3 hours and her brother returned it to the store 7 hours after she rented it, how much does her brother owe her?