Answer:
The missing vertex is (6, -3).
Explanation:
Notice that if you graph the points, the first two points (6, 1) and (-4, 1), the y-coordinates are the same, and in the points (-4, 1) and (-4, -3) the x-coordinates are the same.
To make a rectangle, the fourth point need to have matching y-coordinates with the point (-4, -3) and matching x-coordinates with the point (6, 1). Therefore, the missing vertex is (6, -3).