What is the value of 5k+m when k=-3 and m= -9

Desmond wants to sell his car that he paid $8,000 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 desmond can sell his car for today? 8,000 + 24x 8,000 − 24x 8,000 + 2x 8,000 − 2x

I'll give brainliest if you answer right : )

Which best explains why this triangle is or is not a right triangle?