Percentage by which the average value of mid sized car decreases each year = 8%
Retail value of a car today = v dollars
Amount of decrease in the value of the car after 1 year = (8/100) * v
= 2v/25 dollars
Then
The equation that represents the value of the car after 1 year = v - (2v/25) dollars
= (25v - 2v)/25 dollars
= 23v/25 dollars
So following this expression the value of the mid sized car can be easily determined after 1 year. I hope this is the answer you were looking for and the procedure is also clear to you.