If sales are Rs.40,000; Cost of goods sold is Rs.31,000 and operating expenses are Rs,6,000, the gross profit is ______________.
Calculate closing stock and cost of goods sold. Opening stock Rs. 5,000 ; sales Rs. 16,000; carriage inwards Rs. 1,000, sales return Rs. 1,000; gross profit Rs. 6,000; purchases Rs. 10,000; purchases return Rs. 900.