Sammy bought a new car. The depreciation equation is given by $f(x)=30,000(.85)^{x}$, where $x$ represents the number of years since the purchase of the car, and $f(x)$ represents the value of the car. By what percent does Sammy's car depreciate each year?

Step 1 ：Sammy bought a new car. The depreciation equation is given by \(f(x)=30,000(.85)^{x}\), where \(x\) represents the number of years since the purchase of the car, and \(f(x)\) represents the value of the car. We are asked to find by what percent does Sammy's car depreciate each year.

Step 2 ：The depreciation equation is given in the form of an exponential decay function. The base of the exponent, 0.85, represents the rate of depreciation each year.

Step 3 ：To find the percentage depreciation, we subtract this rate from 1 and multiply by 100.

Step 4 ：Let's calculate the percentage depreciation: \(depreciation\_rate = 0.85\)

Step 5 ：\(percentage\_depreciation = (1 - depreciation\_rate) * 100\)

Step 6 ：Substituting the value of depreciation rate, we get \(percentage\_depreciation = 15.000000000000002\)

Step 7 ：Final Answer: Sammy's car depreciates by approximately \(\boxed{15\%}\) each year.