Correct Answer: 20% gain
Explanation:
CP of 12 pencils = Rs. 12 ∴ SP of 10 pencils = Rs.12 ⇒ SP of 12 Pencils = (12/10) x 12 = Rs.14.40 ∴ Gain per cent = {(14.40 - 12)/12} x 100 = 20%