Task: Question Answering
Input (English): Problem: in some quantity of ghee , 50 % is pure ghee and 50 % is vanaspati . if 20 kg of pure ghee is added , then the strength of vanaspati ghee becomes 30 % . the original quantity was ? 
Options: a ) 25 , b ) 15 , c ) 30 , d ) 45 , e ) 20
Output (English): c