At the start of the financial year, inventory had a value of $15000$. Over the course of the year, sales amounting to $21000$ and purchases amounting to $18000$ took place. Sadly, every item of inventory was stolen on the final day of the financial year. Goods are marked up by $50\%$ when the selling price is worked out. What is the cost of the stolen inventory?
- A$7500$
- B$11000$
- C$19000$
- D$22500$