Start by finding the slope of this points ...
Formula :  y2 - y1 / x2 - x1 
                  0 - 4 /  2  + 6
                     - 4 / 8    the slope is - 1/2 
Now you can be pick on of the either coordinate points....  
If you pick ( 2 , 0 ) it would be ...
 y - 0 = -1/2 ( x - 2 )
If you pick ( - 6 , 4 ) it would be ...
y - 4 = -1/2 ( x + 6) 
So the answer for this question is y - 4 = -1/2 ( x + 6)