By selling an article for $100 a man gains $20 then his gain%?	Options:  A) 25 %  B) 30 %  C) 50 %  D) 20 %  E) 10 %

Rationale: "s . p . = $ 100 gain = $ 20 c . p . = 100 - 20 = 80 gain % = 20 / 80 * 100 = 25 % answer is a"
Answer: A