Task: Question Answering
Input (English): Problem: a man sells an article at a profit of 25 % . if he had bought it at 20 % less and sold it for rs . 10.50 less , he would have gained 30 % . find the cost of the article . 
Options: a ) 30 , b ) 40 , c ) 50 , d ) 60 , e ) 70
Output (English): c