Arcane spell failure of Mithral Breastplate +2

[Rudar Dimble]

What would be the arcane spell failure of a Mithral breastplate +2? 25% or 12,5% (25/2 like with Mithral chain, which is 20/2=10%)

 

[shilsen]

Mithral lowers armor spell failure chances by 10% (DMG, pg.243), so for a breastplate it would drop from 25% to 15%.

 

[Rudar Dimble]

Thanks. Should have searched better though...sorry . Thought it was in some other book.....