Correct Answer - Option 1 : 20

Cost Price = ₹ 500

Initial SP = ₹ (100 + x)/100 of 500 = ₹ (500 + 5x)

New CP = ₹ (100 – x + 10)% of 500 = ₹ 5(110 – x) = ₹ (550 – 5x)

New SP = 130% of (550 – 5x)

⇒ New SP = 715 – 6.5x

⇒ (500 + 5x) – (715 – 6.5x)= 15

⇒ - 215 + 11.5x = 15

⇒ 11.5x = 230

⇒ x = 230/11.5

⇒ x = 20