Task: Question Answering
Input (English): Problem: pipe a can fill a tank in 30 minutes . pipe b can fill the same tank 6 times faster than pipe a . if both the pipes are connected to the tank so that they fill the tank simultaneously , how long will it take for the empty tank to overflow ? 
Options: a ) 4 minutes , b ) 15 / 4 minutes , c ) 192 / 7 minutes , d ) 224 / 7 minutes , e ) 28 minutes
Output (English): b