Task: Question Answering
Input (English): Problem: maxwell leaves his home and walks toward brad ' s house at the same time that brad leaves his home and runs toward maxwell ' s house . if the distance between their homes is 40 kilometers , maxwell ' s walking speed is 4 km / h , and brad ' s running speed is 6 km / h , what is the distance traveled by brad ? 
Options: a ) 16 , b ) 18 , c ) 20 , d ) 24 , e ) 30
Output (English): d