$4.$ Question #$4(8$ points$)$ The annual demand for an item is $10,000$ units. The cost to process an order is $$75$ and the annual inventory holding cost is $20\%$ of item cost. What is the optimal order quantity, given the following price breaks for purchasing the item? What price should the firm pay per unit? What is the total annual cost at the optimal behavior?

$\backslash$table$[[$Quantity$,$Price$],[1-9,$$$2\mathrm{.}95$ per unit$],[10-999,$$$2\mathrm{.}50$ per unit$],[1,000-4,999,$$$2\mathrm{.}30$ per unit$],[5,000$ or more,$$1\mathrm{.}85$ per unit$]]$