How do I Get Relative Coordinates of Objects?

If I have an object on a layer with 0% parallax, how do I get its X and Y coordinates relative to a layer with 100% parallax?

To convert from layer A to B:

X = CanvasToLayerX("B", LayerToCanvasX("A", x, y), LayerToCanvasY("A", x, y))

Y = CanvasToLayerY("B", LayerToCanvasX("A", x, y), LayerToCanvasY("A", x, y))

Very nice. Thank you.