Verified Answer :

Twinee

All these values will assume you are rounding to the nearest tenth

This is what the equation is going to look like
\(Y= Initial Value(1- Rate) ^{12}\)

So when we plug in the values 
\(Y=7800(1-.08)^6\)

From here you will need to follow PEMDAS
\(Y=7800(.92)^6\)

Keep following going through with the equation
\(y=7800(.60)\)

Solve

\(Y=4680\)

Because this is a word problem you have to write it in a written explanation
so

If the car constantly decreases at a rate of 8% over a time period of 6 years, at the end of the time period the car will be worth $4680