Johnny wants to sell his car that he paid $7,000 for 2 years ago. The car depreciated, or decreased in value, at a constant rate each month over a 2-year period. If x represents the monthly depreciation amount, which expression shows how much Johnny can sell his car for today?

7,000 − 24x
7,000 − 2x
7,000 + 24x
7,000 + 2x