By selling an article at Rs.500, a profit of 25% is made. Find its cost price?  Choose the correct choice
A) 400 B) 267 C) 287 D) 480 E) 811

Rationale: "sp = 500 cp = ( sp ) * [ 100 / ( 100 + p ) ] = 500 * [ 100 / ( 100 + 25 ) ] = 500 * [ 100 / 125 ] = rs . 400 answer : a"
Answer: A