A new car worth $21,000 is depreciating in value by $3000 per year. Complete parts (a) through (6).a. Write a formula that models the car's value, y, in dollars, after x years,b. Use the formula from part (a) to determine after how many years the car's value will be 39,000.6. Graph the formula from part (a) in the first quadrant of a rectangular coordinate system. Then, show your solution to part (b) on the graph.a. A formula that models the car's value, y, in dollars, after years is(Type an equation.)