Determining phase difference in wave superposition

franco1991

In wave superposition and interference, of you have 3 waves and you know how much the third wave is out of phase with 2 other waves, how do you determine the other 2 waves phase difference relative to each other?

For example. A waveform (Wave-A) has a phase-difference of 120 degrees in relation to Wave B, and a 45 degree phase difference with Wave C, how do you determine Wave B's phase difference relative to Wave C, or Wave C's phase difference relative to B?