Edna needs a safer car to drive. She likes to travel a lot, so she is looking for a small SUV. She is trying to decide between buying a new or used car. After doing some research, she finds out that most cars lose value each year by a process known as depreciation. You may have heard before that a new car loses a large part of its value in the first 2 or 3 years and continues to lose its value, but more gradually, over time. That is because the car does not lose the same amount of value each year, but it loses approximately the same percentage of its value each year. What kind of model would be most useful for calculating the value of a car over time?