Task: Question Answering
Input (English): Problem: a cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 8 hours . if both the taps are opened simultaneously , then after how much time will the cistern get filled ? 
Options: a ) 7.5 , b ) 7.4 , c ) 7.9 , d ) 7.2 , e ) 8.0
Output (English): e