A shop owner professes to sell his articles at certain cost price but he uses false weights with which he cheats by 20% while buying and by 20% while selling. What is his percentage profit? Answers.
A) 10.22 %
B) 20.22 %
C) 21.22 %
D) 50 %
E) ca n ' t be calculated

Rationale: "the owner buys 100 kg but actually gets 120 kg ; the owner sells 100 kg but actually gives 80 kg ; profit : ( 120 - 80 ) / 80 * 100 = ~ 50 % answer : d ."
Answer: D