With explanation when calculating !!!

15 Two machining operations, A (3 minutes per part) and B (10 minutes per part), are per- formed sequentially to manufacture a part. Machines A and B produce 5 percent and 6 percent defective items, respectively. The factory operates 8 hours each day, 5 days per week, 4.2 weeks per month. Every day each machine needs 0.30 hour for being set up. Find the machine fraction for each type (A and B) if we need to handle a demand of 1000 items per month. Use a machine-up factor equal to 85 percent for each machine. A B