Accounting for labour

Q) A business employs two grades of labour in its production department. Grade A workers are considered direct labour employees, and are paid $10 per hour. Grade B workers are considered indirect labour employees, and are paid $6 per hour. In the week just ended, Grade A labour worked 30 hours of overtime, 10 hours on a specific customer order at the customer's request, and the other 20 hours as general overtime. Grade B labour worked 45 hours of overtime, as general overtime. Overtime is paid at time-and-one-half. What would be the total amount of pay for overtime worked in the week that is considered to be a direct labour cost? A. $50 B. $150 C. $285 D. $350 This question is from Kaplan and I know that Grade B labourers overtime will not be considered to be a direct cost since they are indirect labour employees AND I believe that only the 10 hours of specific overtime by Grade A labour employees will be considered as direct cost, right? Hence, the answer should be A because 10hrs x $10 x .50 But the answers at the back of the book say D and the method they have shown INCLUDES the 30 hours of general overtime. Please help. =)