Maximize the function $P = 10 x - 6 y$ subject to

$$\left\{\begin{array}{rcr} x & \geq & 0 \cr y & \geq & 0 \cr 2 x + 6 y & \leq & 12 \cr 6 x + 3 y & \geq & 18 \end{array}\right.$$

What are the corner points of the feasible set?

The maximum value is and it occurs at . Type "None" in the blanks provided if the maximum does not exist.