In this case, the total bill used for the car is $572. From that bill $248 definitely used for the parts, then the other is used for the labor payment. Then to count how much the labor payment is, you need to subtract total bill with parts bill. The equation would be:
Labor payment = $572 - $248 = $324
From here you can count how many hours the labor did too. It would be: $324/ (30$/hour) = 10.8 hours
