Help please ​

I think the answer is (B), because: After 12 years, the resale price finally hit 0, so 400/12=33.333 and goes on forever. 

So, the value drops $100 every 3 years, to make it, so it can work.

Since this is a straight line....The slope will give us the rate of change

We have the points   (0, 400)  and  (12 ,0)

slope  =   [ 400 - 0 ] / [ 0 - 12 ] =  -400 /12    =  -100/3....just as Mathtoo found !!!