Task: Question Answering
Input (English): Problem: a train overtakes two persons who are walking in the same direction in which the train is going , at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively . find the length of train ? 
Options: a ) 45 m , b ) 50 m , c ) 55 m , d ) 60 m , e ) 65 m
Output (English): b