How many corner points does the feasible region of $x + y \le 4, x + 3y \le 6, x \ge 0, y \ge 0$ have?

Explanation

1. 01

   Find where the boundary lines, the axes included, meet, and keep the meeting points that satisfy every constraint.

2. 02

   They are $(0, 0)$, $(0, 2)$, $(3, 1)$, $(4, 0)$: 4 in all.