Urgent: Inventory Model. Solve step by step. thanks

Question:

A supplier offer the following discount structure on purchases of any single item:

0 < Q < 1000 $5.00 per unit

1000 Q < 2000$4.90 per unit

2000 Q $4.75 per unit

The discount applies to all units. For each of the following items treated separately, what is the appropriate order quantity to use, assuming a common value ofi = 0.30 $/$/year and an ordering cost A = $25 per order

Item D (units/year)

1 10,000

2 1,000

3 4,000