Question

what is the image of point (4,3) if the rotation is -180 degrees?

Answer 1

Same as if the rotation was 180 degrees :-)

Answer 2

so its 180 degrees

Answer 3

Yes, 180 and -180 degrees are equivalent rotations. Our point goes from (4,3) to (-4,-3), just as if you had turned the paper 2 90 degree turns either to the right or to the left.