Task: Question Answering
Input (English): Problem: two tains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post . if the length of each train be 125 metres , in what time ( in seconds ) will they cross each other travelling in opposite direction ? 
Options: a ) 6 , b ) 14 , c ) 16 , d ) 20 , e ) 18
Output (English): a