The sum of cost price and marked price of article 'A' and that of article 'B' are Rs. 10,500 and Rs. 16,000, respectively. Articles 'A' and 'B' were marked 10% and 300% above their respective cost prices. If both the articles were sold after allowing a discount of 10%, then find the difference between their selling prices.

Let the cost price of article 'A' be Rs. 'x' Therefore, marked price of article 'A' = 1.10 × x = Rs. '1.1x' According to the question, 1.1x + x = 10500 Or, 2.1x = 10500 Or, x = (10500 / 2.1) = 5000 Marked price of article 'A' = 1.1 × 5000 = Rs. 5500 Selling price of article 'A' = 0.9 × 5500 = Rs. 4950 Similarly, let the cost price of article 'B' be Rs. 'y' Marked price of article 'B' = 4y y + 4y = 16000 Or, 5y = 16000 Or, y = (16000 / 5) = 3200 Marked price of article 'B' = 4 × 3200 = Rs. 12800 Selling price of article 'B' = 0.9 × 12800 = Rs. 11520 Required difference = 11520 − 4950 = Rs. 6570