Inventory management problem

Total annual demand $D=\frac{4800}{y}r$

Carrying cost is estimated to be $10\%$ of unit cost

Order cost $S=$$$\frac{120}{?}$ order

Price per unit $P=$$$350$ if fewer than $100$ are ordered;

$$325$ if between $100$ and $199$ are ordered; and

$$300$ if $200$ or more are ordered

Do a complete "EOQ with Discount" calculation and determine the optimal order quantity.

Please show all calculations.