A dealer marks his goods at 20% above the cost price and allows a discount of 15% on the marked price. What is his gain or loss percentage?

Correct option is C

MP = 120% × CP
MP / CP = 120 / 100 = 6 / 5
ATQ,
CP / MP = (100 - D%) / (100 + P%)
5 / 6 = (100 - 15) / (100 + P%)
5 / 6 = 85 / (100 + P%)
(100 + P%) = (85 × 6) / 5
P% = 102 - 100 = 2%