303. The phases of a turn are rigid, but the actions taken during those steps can be done in any order, unless otherwise specified.
303.1. Game Actions of any nature are performed one at a time and are executed completely.
303.2. Game Actions cannot be performed simultaneously for any reason.
303.2.a. If one or more actions, game effects, or Triggered Abilities are activated simultaneously, then Turn Order is referenced to organize the sequence of actions. See rule 375. Triggered Abilities for more information.