Incorporeal Creature with DR

[OgeXam]

Anybody know for sure if you would apply the DR then do 50% damage or 50% damage then apply DR?

For instance a pixie ghost has DR 10/cold iron.

It gets hit by a greatsword +2 for 30 damage.
Do I apply DR 30 => 20 then 50% => 10 damage applied to pixie ghost?
Or do I apply 50% 30 => 15 then DR => 5 damage applied to pixie ghost?

[Kolokotroni]

DR only applies do damage you actually take. So it would be 50% and then the DR.

[Senevri]

Some types of DR go poof with Ghost template, however.