The cost of 20 articles is equal to selling price of 10. Find the gain or loss percent? Choose the correct choice from the following.
A) 50 %
B) 100 %
C) 25 %
D) 15 %
E) 60 %

Rationale: c . p . of each article be $ 1 c . p . of 10 articles = 10 gain % = 10 / 10 * 100 = 100 % answer is b
Answer: B