Task: Question Answering
Input (English): Problem: a and b can do a piece of work in 10 days . with the help of c they finish the work in 3 days . c alone can do that piece of work in ? 
Options: a ) 15.5 days , b ) 4.3 days , c ) 17.5 days , d ) 16.5 days , e ) 18.5 days
Output (English): b