Consider the Linear Programming Problem (LPP): Maximize $z = 30x + 60y$ subject to constraints $x + 2y \leq 12$, $2x + y \leq 12$, $4x + 5y \geq 20$, $x \geq 0$, $y \geq 0$. Then the number of corner points of the feasible region is
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Always consider only feasible intersections (satisfying all inequalities).