Let $T \in \text{Exp}(\theta)$ be an D214: Exponential random positive real number.
Let $t \in \mathbb{R}$ be a D993: Real number.

Then \begin{equation} \mathbb{P}(T \leq t) = \left( 1 - e^{- \theta t} \right) I_{t \in [0, \infty)} \end{equation}