Task: Question Answering
Input (English): Problem: if two students starting from same point , walking in the opposite directions with 6 km / hr and 9 km / hr as average speeds respectively . then the distance between them after 4 hours is ? 
Options: a ) 65 km , b ) 55 km , c ) 15 km , d ) 60 km , e ) 75 km
Output (English): d