The cost price of article X is Rs. 'a + 1000' and it is marked 60% above its cost price. The profit earned on article X is Rs. 1000 when a discount of 12.5% is given. If the cost price of article B is Rs. 'a + 500' and selling price is 14.28% less than selling price of article X, then find the profit percentage earned on selling article B?