Task: Question Answering
Input (English): Problem: set k contains every multiple of 6 from 18 to 306 inclusive . if w is the median of set k , and x is the average ( arithmetic mean ) of set k , what is the value of w - x ? 
Options: a ) - 6 , b ) - 3 , c ) 0 , d ) 3 , e ) 6
Output (English): c