Task: Question Answering
Input (English): Problem: a pump can fill a tank with a water in 2 hours . because of a leak , it took 2 and 4 / 5 hours to fill the tank . the leak can drain all the water of the full tank in how many hours ? 
Options: a ) 4 , b ) 5 , c ) 6 , d ) 7 , e ) 8
Output (English): d