Which of the following functions represents the inverse of f(x)=x+15f(x) = x + 15f(x)=x+15?
f−1(x)=x+15f^{-1}(x) = x + 15f−1(x)=x+15
f−1(x)=15−xf^{-1}(x) = 15 - xf−1(x)=15−x
f−1(x)=x−15f^{-1}(x) = x - 15f−1(x)=x−15
f−1(x)=x15f^{-1}(x) = \frac{x}{15}f−1(x)=15x