Task: Question Answering
Input (English): Problem: a and b can do a piece of work in 48 days , a and c can do it in 60 days , b and c can do it 72 days . in what time can c alone do it ? 
Options: a ) 84 days , b ) 84 ½ days , c ) 85 days , d ) 87 days , e ) 89 days
Output (English): c