In 2006, Troy bought a new car for $25,500. The car was worth $18,000 in the year 2008. If Troy knows that the value of the car depreciated linearly, what was the annual rate of change of the car's value? Round your answer to the nearest hundredth if necessary.​

A function can only have 1 y value for each x value. To check this on a graph you would use the vertical line test.

To pass the vertical line test, the graphed line can only touch the vertical line in one place.

The pictured graph is a function, because it would pass the vertical line test.

The answer is A.