Task: Question Answering
Input (English): Problem: a can complete a project in 20 days and b can complete the same project in 30 days . if a and b start working on the project together and a quits 5 days before the project is completed , in how many days total will the project be completed ? 
Options: a ) 12 , b ) 15 , c ) 18 , d ) 21 , e ) 24
Output (English): b