Answer:
The value of the car after four year is $9396.108 .
Option (b) is correct i.e about $9400 .
Explanation:
The exponential decreasing function is given by

Where a is the initial value , r is the rate of interest in decimal form and t is the time in years .
As given
Mr.henry buys a car for $18,000. the value of the car decreases about 15% each year. after 4 years .
a = $18000
15% is written in the decimal form .

= 0.15
t = 4 years
Putting all the values in the formula



y = $9396.108
Therefore the value of the car after four year is $9396.108 .
Option (b) is correct i.e about $9400 .