A 6-ft-tall person walks away from a 12-ft lamppost at a constant rate of 3.2ft/sec. What is the rate at the tip of the person's shadow moves away from the lamppost when the person is 8ft away from the lamppost?
At the moment the person is 8ft from the post, the tip of their shadow is moving away from the post at a rate of at a rate of ___ ft/sec.