Task: Question Answering
Input (English): Problem: two pipes a and b can fill a tank in 36 hours and 46 hours respectively . if both the pipes are opened simultaneously , how much time will be taken to fill the tank ? 
Options: a ) 20.195 hrs , b ) 21.195 hrs , c ) 22.195 hrs , d ) 23.195 hrs , e ) 20.495 hrs
Output (English): a