Brett opened a margin account with a discount brokerage firm. Three months ago, he sold short 100 shares of stock; the market price of the stock at that time was $63.50. Today it is priced at $47.30. If he decides to buy to close (i.e., buy 100 shares of stock in order to close his open short position) what will be his net gain or loss? (For purposes of this problem assume that the cost of opening the position was $5, the cost of closing the position was $5 and margin interest was $40.)