rotation of 90° counterclockwise about the origin
rotation of 180° about the origin
reflection across the x-axis
rotation of 90° clockwise about the origin
Try a few points and you'll see what happens. For example if you had the point (2,3) in the first quadrant, you'll end up with the point (-2,-3) in the third quadrant.
That's equivalent to a rotation of 180° about the origin.