Answer:
13.9%
Step-by-step explanation:
The value of car is modeled as:
[tex]V(t)=21,000(0.861)t[/tex]
Here we can see that, each year Nathan has considered 0.861 of the previous year value or we can say that Nathan has considered 86.1% of the previous year value. So,
[tex]100-86.1=13.9[/tex]
We subtract the percentage value considered from 100 to find out the percentage decrease in the value of the car.
The value of new car is decreasing by 13.9% each year.