Task: Question Answering
Input (English): Problem: a can do a work in 20 days , b in 30 days . a alone start the work after 10 days he left work . in how many days b can finish the work ? 
Options: a ) 30 days , b ) 25 days , c ) 20 days , d ) 10 days , e ) 15 days
Output (English): e