Let $P = (\Omega, \mathcal{F}, \mathbb{P})$ be a D1159: Probability space.
Let $E, F \in \mathcal{F}$ each be an D1716: Event in $P$ such that

(i)	$\mathbb{P}(F) > 0$

Then \begin{equation} \mathbb{P}(E \mid F) = \frac{\mathbb{P}(E \cap F)}{\mathbb{P}(F)} \end{equation}