Reflecting across the x-axis, the x-coordinate ALWAYS remains the same, but the y-coordinate is transformed into its opposite. If you forget this, fold along the x line, and you should be able to figure it out. Reflecting across the y-axis, the y-coordinate ALWAYS remains the same, but the x-coordinate is transformed into its opposite. If you forget this, fold along the y line, and you should be able to figure it out.