Task: Question Answering
Input (English): Problem: a , b , c can complete a piece of work in 3,9 and 15 days respectively . working together , they will complete the same work in how many days ? 
Options: a ) 45 / 23 , b ) 55 / 23 , c ) 61 / 57 , d ) 12 / 13 , e ) 22 / 23
Output (English): a