Task: Question Answering
Input (English): Problem: two trains start from p and q respectively and travel towards each other at a speed of 50 km / hr and 40 km / hr respectively . by the time they meet , the first train has travelled 1 ookm more than the second . the distance between p and q is 
Options: a ) 500 km , b ) 600 km , c ) 700 km , d ) 900 km , e ) 400 km
Output (English): d