Answer:
Economic Production Quantity = 233.55 boxes per month =234 Boxes
Step-by-step explanation:
EPQ =

K= Set up cost = $60
D =Demand rate = 400
H= holding cost = $2
x= Demand Rate / Production Rate = 400/ (36*20) =0.56
substitute values into formula
EPQ =

= 233.55 Boxes per month