Final answer:
Adrianna's car has a 3-year growth factor of 0.76, reflecting its 24% value depreciation every three years.
Step-by-step explanation:
The 3-year growth factor for the value of Adrianna's car is calculated on the basis of the car's depreciation rate of 24% every 3 years. Since the car decreases in value, the growth factor would be less than 1. To find the growth factor, we subtract the percentage of decrease from 1 (100%). The growth factor is 1 - 0.24 which equals 0.76. Therefore, every 3 years, the car's value will be multiplied by 0.76 to find its new value.