a. The y-intercept of the graph is 35,000, which represents the original purchase price of the car. Therefore, the car was purchased for $35,000.
b. We can see from the graph that the car's value becomes 0 after 9 years. Therefore, the car totally depreciates after 9 years.
c. The equation of a straight line can be written as y = mx + b, where m is the slope and b is the y-intercept. The slope of the graph is the rate of depreciation, which is -4000. The y-intercept is the original price of the car, 35000.
So the equation of the straight line depreciation graph is: y = -4000x + 35000
This equation represents the value of the car, where y is the value of the car (in dollars) x is the number of years since the car was purchased and -4000 is the rate of depreciation and 35000 is the original price of the car.