Correct Answer: Rs. 800
Explanation:
Let the marked price be Rs. N ∵ C.P. = (N - 25% of N) = 3N / 4 ⇒ S.P. = (3N / 4 + 10% of 3N / 4) = 33N / 40 But, 33N / 40 = 660 ∴ N = 800