Final answer:
The rule/formula applied in the expression P(X > 14) = 1 - P(X ≤ 14) is the Complement rule.
Step-by-step explanation:
The rule/formula applied in the expression P(X > 14) = 1 - P(X ≤ 14) is the Complement rule. The Complement rule states that the probability of an event not occurring is equal to one minus the probability of the event occurring. In this case, the event is X > 14, and the complement of this event is X ≤ 14.