Let $x, y \in [0, \infty)$ each be an D4767: Unsigned real number such that
(i) | $x + y \neq 0$ |
Then
(1) | \begin{equation} \frac{x}{x + y}, \frac{y}{x + y} \in [0, 1] \end{equation} |
(2) | \begin{equation} \frac{x}{x + y} + \frac{y}{x + y} = 1 \end{equation} |