Need well defined and detailed solution to all parts

Problem IC5 ** A contractor has to supply 10,000 bearings per day to an automobile manufacturer. He finds that, when he starts production run, he can produce 25,000 bearings per day. The cost of holding a bearing in stock for a year is Rs 2 and the set up cost of a production run is Rs 1800 . What is the economic production lot size? \{Assume 300 working days/yr.\}