Task: Question Answering
Input (English): Problem: if a , b and c together can finish a piece of work in 4 days . a alone in 12 days and b in 18 days , then c alone can do it in ? 
Options: a ) 7 days , b ) 3 days , c ) 9 days , d ) 8 days , e ) 2 days
Output (English): c