Task: Question Answering
Input (English): Problem: jonathan can type a 20 page document in 50 minutes , susan can type it in 30 minutes , and jack can type it in 24 minutes . working together , how much time will it take them to type the same document ? 
Options: a ) 5 minutes , b ) 11 minutes , c ) 15 minutes , d ) 18 minutes , e ) 20 minutes
Output (English): b