#### Answer

$f^{-1}(1000)$ represents the amount of dollars used/spent to build 1000 cars.

#### Work Step by Step

$f(x)$ represents the number of cars that can be built for $x$ dollars.
This means that the inverse function represents the amount of dollars used/spent to build a certain number of cars.
Thus, $f^{-1}(1000)$ represents the amount of dollars used/spent to build 1000 cars.