Task: Question Answering
Input (English): Problem: two trains of length 100 m and 200 m are 100 m apart . they start moving towards each other on parallel tracks , at speeds 18 kmph and 72 kmph . in how much time will the trains cross each other ? 
Options: a ) 8 , b ) 16 , c ) 11 , d ) 12 , e ) 21
Output (English): b