Suppose that the online retailer Amazon needs to use larger and larger cardboard boxes over time. One particular model of a tall cardboard box with a square base keeps being changed so that its volume increases by 80 cubic inches each year, while its height increases by 0.5 inches each year. What is the rate of change of the width of the box when the box has a height of 30 inches and a width of 20 inches? Show all of your work.