The worth of car at the start of 2014 = $12000
The value of the car decreased 30% every year.
At start of 2015:
30% of 12000 =
= 3600
So, the value of the car at start of 2015 = 12000-3600 = $8400.
At start of 2016:
30% of 8400 =
= 2520
So, the value of the car at start of 2016 = 8400-2520 = $5880.
At start of 2017:
30% of 5880 =
= 1764
So, the value of the car at start of 2017 = 5880-1764 = $4116.
So, the value of his car at the start of 2017 is $4116.