So the Y coordinate of all these three different curves is exactly the same. It's around zero point 98, which is equivalent to 98% saturation of hemoglobin. Now, when we go into the exercising tissues, the concentration of our oxygen drops to about 20 mercury. And notice that at this particular point, we have three different Y coordinates. For this black curve, the Y coordinate is around zero point 32. For the blue curve, the coordinate is around zero point 21.