A man buy a book in Rs50 & sale it Rs90. What is the rate of profit ???	Choose the correct answer:
A) 10 % B) 80 % C) 30 % D) 25 % E) 28 %

Rationale: cp = 50 sp = 90 profit = 90 - 50 = 40 % = 40 / 50 * 100 = 80 % answer : b
Answer: B