Boy sells a book for Rs. 630 he gets a loss of 10 %, To gain 10%, what should be the SP?
Choose the correct choice from the following answers:	A) 430	B) 450	C) 550	D) 770	E) 660

Rationale: "cost price = 630 / 90 x 100 = 700 to gain 10 % = 700 x 10 / 100 = 70 sp = cp + gain = 700 + 70 = 770 answer : d"
Answer: D