Disjunction Rules
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
Mutually exclusive: P(A or B) = P(A) + P(B). Otherwise: add, then subtract P(A and B).
Show
One die, "2 or 5": add. "King or heart": add, subtract the king of hearts — counted twice.
Watch for
The subtraction exists because inclusive-or double-counts the overlap. Video 120's distinction, now with arithmetic.