Answer:
(2, 8)
Step-by-step explanation:
The midpoint of a line segment is calculated by taking the average of the x and y coordinates.
(2, 8) is the coordinates of b, because the midpoint is ( (6+2)/2, (-4+8)/2) ,which is (4,2).
Hope this helped, and if it did, please consider giving me a brainliest. (: