Task: Question Answering
Input (English): Problem: a alone can do a piece of work in 6 days and b alone in 8 days . a and b undertook to do it for rs . 3600 . with the help of c , they completed the work in 3 days . how much is to be paid to c ? 
Options: a ) s . 375 , b ) s . 450 , c ) s . 600 , d ) s . 800 , e ) s . 850
Output (English): b