A mail order house uses 18,000 specialty boxes a year. Annual holding costs $0.60 per box Ordering cost 6.00 $ per order Their vendor has provided the following price schedule: Number of boxes Price per box 1-499 3.00 $ 500-999 2.95 $ 1,000-1,499 2.90 $ 1,500 or more 2.85 $ 8 a. What is the optimal order quantity for the mail house? b. What is the total overall annual cost if the company orders at the optimal order quantity?