The light reflected from a film as in (a) is analysed with a spectrometer. At normal incidence it is found that the spectrum has a minimum at wavelength 600 nm. As the angle of incidence is increased to 54°, the position of this minimum (i.e., this order of interference) shifts to 480 nm, and the next minimum comes to be at 600 nm. What are the orders of interference of the two minima involved?