Lumley Pty Ltd has a perpetual inventory system and sells only one product. 80 items of inventory/stock costing $30 each were in the store at the beginning of June. 20 more items were purchased for $50 each on the 12th June. 90 items were sold for $100 each on the 28th June. Assuming a WEIGHTED AVERAGE system is used for inventory records, what was the cost of goods sold for the 28th June sale?