A man buys an article for $100. and sells it for $120. Find the gain percent?  Select
A) 10 %  B) 15 %  C) 25 %  D) 20 %  E) 30 %

Rationale: "c . p . = $ 100 s . p . = $ 120 gain = $ 20 gain % = 20 / 100 * 100 = 20 % answer is d"
Answer: D