Let $P = (\Omega, \mathcal{F}, \mathbb{P})$ be a D1159: Probability space such that

(i)	$E, F \in \mathcal{F}$ are each an D1716: Event in $P$
(ii)	$E \subseteq F$ is a D78: Subset of $F$

Then \begin{equation} \mathbb{P}(E \triangle F) = \mathbb{P}(F) - \mathbb{P}(E) \end{equation}