Two were bought at 792 Rs. each so total cost price 792*2= 1584 Rs. Now take 10 percent of 792 that is 10/100 * 792 = 79.2 Rs. Now one is sold at profit of 10 percent so add 79.2 to 792 (original cost price) = 871.2 and other is sold at a loss of 10 percent so deduct 79.2 from 792 = 712.8. Now add both sale prices i.e 871.2 + 712.8 = 1584 Rs, which is the same as cost price . so no profit or loss.. The questions seem easy, but they are tricky. A slight misjudge can cost you a mcq.