D&D 5E heavy armor mastery + resistance?

[PnPgamer]

In what order does these two damage reductions work? Is there phb page that says so?

 

[Paraxis]

DAMAGE RESISTANCE AND VULNERABILITY

Some creatures and objects are exceedingly difficult or unusually easy to hurt with certain types of damage.

If a creature or an object has resistance to a damage type, damage of that type is halved against it. If a creature or an object has vulnerability to a damage type, damage of that type is doubled against it.

Resistance and then vulnerability are applied after all other modifiers to damage. For example, a creature has resistance to bludgeoning damage and is hit by an attack that deals 25 bludgeoning damage. The creature is also within a magical aura that reduces all damage by 5. The 25 damage is first reduced by 5 and then halved, so the creature takes 10 damage.

From the online basic rules, away from my books at the moment.

 

[PnPgamer]

Ok thanks for the info!