Task: Question Answering
Input (English): Problem: a and b can do a piece of work in 18 days ; band c can do it in 24 days a and c can do it in 36 days . in how many days will a , band c finish it together ? 
Options: a ) 15 days , b ) 12 days , c ) 8 days , d ) 16 days , e ) 9 days
Output (English): d