A shop owner professes to sell his articles at certain cost price but he uses false weights with which he cheats by 12% while buying and by 20% while selling. What is his percentage profit?  Answers:
A) 10.22 %  B) 20.22 %  C) 21.22 %  D) 40 %  E) ca n ' t be calculated

Rationale: "the owner buys 100 kg but actually gets 112 kg ; the owner sells 100 kg but actually gives 80 kg ; profit : ( 112 - 80 ) / 80 * 100 = ~ 40 % answer : d ."
Answer: D