I have got:
Prime: C# E F D D# B Bb A G# F# C G (we were given this to work from)
I worked out:
Retrograde: G C F# G# A Bb D# D F E C#
Inversion (the bit that has so far taken 6 attempts): C# Bb A C B D# E F G# C# D# G# - This can't be right, as I have somehow ended up with two C#'s and 2 D#'s and 2 G#'S
Retrograde Inversion: G# D# C# G# F E D# B C A Bb C#
I'm really confused with the inversion bit, on the first attempt I got the 3rd note wrong, throwing the whole thing out by 2 semitones...