Step 1: Analyze the given constraints.
\[
x \geq 0, \quad y \geq 0, \quad x + y \geq 4
\]
These constraints represent:
\begin{itemize}
\( x \geq 0 \): Right of the y-axis.
\( y \geq 0 \): Above the x-axis.
\( x + y \geq 4 \): A line passing through points \( (4, 0) \) and \( (0, 4) \).
\end{itemize}
Step 2: Determine the feasible region.
The feasible region lies in the first quadrant above the line \( x + y = 4 \). The intersection points (corner points) are:
\[
(4,0), \quad (0,4)
\]
Final Answer:
\[
\boxed{2}
\]