Task: Question Answering
Input (English): Problem: ajay and balu together can do a piece of work in 12 days . balu and charan together can do the same work in 16 days . after ajay has been working at it for 5 days and balu for 7 days , charan finishes it in 13 days . in how many days will charan alone be able to do the work ? 
Options: a ) 16 days , b ) 24 days , c ) 36 days , d ) 48 days , e ) 58 days
Output (English): b