Julie Ltd is a retailer selling USB sticks and uses the perpetual inventory system and the Weighted Average Cost to value inventories. On August 1, there were 10,000 units valued at $30,000 in the beginning inventory. On August 10, 20,000 units were purchased for $6 per unit. On August 15, 24,000 units were sold for $12 per unit. The amount relating to cost of sales on August 15 was