The frequency of a note on the piano, in Hz, is related to its position on the keyboard by the function f(n) = 440 - 21 where n is the number of keys (both white and black) above or below the note concert A. (Concert A, with a frequency of 440 hertz, is the frequency of the A key above the middle C key on a piano.) Using this function f(n), find the position n (relative to the position of concert A) of the piano key that has a frequency of 55 Hz. (In other words, what number n do you need to input in the function f (n) for f (12) = 55?) Show your steps and explain your solution process. ​