Task: Question Answering
Input (English): Problem: two pipes can fill a tank in 30 minutes and 20 minutes . an outlet pipe can empty the tank in 15 minutes . if all the pipes are opened when the tank is empty , then how many minutes will it take to fill the tank ? 
Options: a ) 48 , b ) 54 , c ) 60 , d ) 66 , e ) 72
Output (English): c