Task: Question Answering
Input (English): Problem: a can do a job in 30 days and b can do it in 30 days . a and b working together will finish twice the amount of work in - - - - - - - days ? 
Options: a ) 14 days , b ) 26 days , c ) 30 days , d ) 31 days , e ) 39 days
Output (English): c