accounting for labour

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 working: basic pay = 10 X 10 =100 plus overtime which is considered a direct cost because of a specific customer order. 10 X 10X 50% = 50 My final answer is 150. but the answer is D - 350. Can you explain why is that so? Thanks in advance