Inverse function Khan Academy

Question

I'm doing an exercise on inverse functions on Khan Academy and cannot get with the first exercise. Where to find number $93$? There is no such number in the table...

Answer 1

Hint: what is the inverse function $f^{-1}$?

Answer 2

By the definition of the inverse fuction, $$f^{-1}\left ( f(93) \right )=93.$$