A shopkeeper marked the price of a book above 60% of its cost price and gives two successive discounts of x%, he still makes a profit of 15.6%. Find value of x. एक दुकानदार अपनी लागत मूल्य के 60% से ऊपर एक पुस्तक की कीमत अंकित करता है और x% के दो क्रमिक छूट देता है, वह अभी भी 15.6% का लाभ कमाता है। x का मान ज्ञात कीजिए।

Let CP = 100. Marked price = 160 (60% above CP). Two successive discounts of x% means final price = 160×(1-x/100)². This equals SP at 15.6% profit = 115.6. So 160×(1-x/100)² = 115.6. (1-x/100)² = 115.6/160 = 0.7225. 1-x/100 = √0.7225 = 0.85. x/100 = 0.15. x = 15%. Since 15% is not in options A-D (12%, 10%, 20%, 25%), answer is E.