vorzuberieten?

Vorzubereiten appears in the following sentence in level 2 14.4:
Sandra hat Stephanie für ein paar Stunden weggelockt und hatte Zeit alles vorzubereiten.
Translated as:
Sandra lured Stephanie away for a few hours and had time to prepare everything.
I am puzzled by vorzuberieten, it doesn't seem to be in any of the dictionaries.
Google translate has it as to be prepared.
What is the difference between bereiten, vorbereiten and vorzubereiten?

I found another similar example of a mysterious "zu"
auszupacken in 14.5 Christmas vocab

I found the answer to this by chance while looking up some other  grammar.
When you have a separable verb, the "zu" goes between the prefix and the main verb.
And you need the zu rather than just the infinitive in this situation where you want "to prepare" or "to unpack".

Yes, I understand how it can irritate that we along with "bereiten" have the extensions "vorbereiten", "zubereiten" and  "vorzubereiten".  As you said they are the infinitive verb versions.  "vorbereiten" and  "zubereiten" are often exchangeable. 

Gruss

Paul