Task: Question Answering
Input (English): Problem: a and b complete a work in 4 days . a alone can do it in 6 days . if both together can do the work in how many days ? 
Options: a ) 3.75 days , b ) 3.7 days , c ) 3.6 days , d ) 2.4 days , e ) 5.75 days
Output (English): d