Sometimes when saying goodbye people would say
Machen Sie es gut.
or
Mach es gut.
What would be good answers to this? I can think of
Gleichfalls.
Sie auch. / Du auch.
Sometimes when saying goodbye people would say
Machen Sie es gut.
or
Mach es gut.
What would be good answers to this? I can think of
Gleichfalls.
Sie auch. / Du auch.
In my opinion, the best answer is your last choice - "Sie auch. / Du auch."
"Gleichfalls/Danke, Gleichfalls!" is more commonly used for things like "have a nice day/weekend" or "Viel Glück" etc.
Even if it should be "correct" and makes sense here, I have never head someone responding "Gleichfalls" to "Machs gut!"
And of course, as already said, simply saying "Danke" (or anything equal) is rude, as you imply you do not care if your opposite is having a good time or not - while he/she does.