Question 1045944
 bought a car for $10,000 
four years lost 20% ($2000) | Depreciated $500 per year
Let x represent the number of years...
Depreciate Value = 10000 - 500x

when the car is only worth $1,000?
1000 = 10000 - 500x
500x = 10000-1000
500x = 9000
x = 9000/500
x = 18 years, when the car is only worth $1,000