Task: Question Answering
Input (English): Problem: a can do a piece of work in 80 days . he works at it for 10 days b alone finishes the remaining work in 42 days . in how much time will a and b working together , finish the work ? 
Options: a ) 25 , b ) 30 , c ) 20 , d ) 32 , e ) none of them
Output (English): b