Task: Question Answering
Input (English): Problem: by selling an article at rs . 1000 , a shopkeeper makes a profit of 25 % . at what price should he sell the article so as to make a loss of 25 % ? 
Options: a ) s . 600 , b ) s . 480 , c ) s . 500 , d ) s . 450 , e ) s . 550
Output (English): a