Answer: The transformation that moves R sub 180 (r sub x-axis(P)) back to P is a reflection across the x-axis. A reflection across the x-axis is a transformation in which each point is reflected over the x-axis so that its image has the same x-coordinate but a y-coordinate of opposite sign. In other words, if a point P has coordinates (x, y), then its reflection R sub 180 (P) has coordinates (x, -y). By reflecting R sub 180 (P) back across the x-axis, we obtain the original point P with the same coordinates (x, y).
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