How does blessed aura and staff wrapping of enchanting stack?

like the title says, i want to know that. And yes, i did search.

They do.

I believe in another post that one percent is calculated, then a percentage of that new number is calculated. For example, say blessed aura is 20%, and you have a 20% staff wrap. Your base skill length is 10 seconds, and the final length will be 14.4 seconds. (10+20%)+20%. Not 14 seconds which would be 10+40%. Although you may want somone more knowledgable on this subject to comment.

How?
For example:
blessed aura 30%
wrapping 20%

is the outcome 50%? 30+20
or is the outcome 56%? 1.3*1.2=1.56

It is the second outcome, 56%. At least that is what I was lead to believe.