What is actually transformed in quarter wave transformer?
This is the formula that is interesting: -

\$Z_{IN} = \dfrac{Z_1^2}{R_L}\$

As George has "said" in a comment - if you have a 75 ohm system feed and you want to deliver the full power to a 33 ohm load, use a quarter wavelength of 50 ohm cable and the formula numerically becomes: -

\$Z_{IN} = \dfrac{50^2}{33}\$ = 75.75 ohms. (Near enough)