If 5% more is gained by selling an article for Rs. 600 than by selling it for Rs. 580, the cost of the article is?	Options:
A) 127
B) 688
C) 400
D) 121
E) 123

Rationale: "let c . p . be rs . x . then , 5 % of x = 600 - 580 = 20 x / 20 = 20 = > x = 400 answer : c"
Answer: C