The cost price of an article is 64% of the marked price. Calculate the gain percent after allowing a discount of 20%? Choices:
A) 37.5 %
B) 48 %
C) 50.5 %
D) 52 %
E) 25 %

Rationale: "explanation : let marked price = rs . 100 . then , c . p . = rs . 64 , s . p . = rs . 80 gain % = 16 / 64 * 100 = 25 % . answer : option e"
Answer: E