Explanation: On plotting the constraints $\mathit{x}=3$, $\mathit{x}=9,\mathit{x}=\mathit{y}$ and $\mathit{x}+\mathit{y}=14$, we get the following graph. From the graph given below it clear that feasible region is $\mathrm{ABCDEA}$, including corner points $\mathrm{A}\left(9,0\right),\mathrm{B}\left(3,0\right),\mathrm{C}\left(3,3\right),\mathrm{D}\left(7,7\right)$ and $\mathrm{E}\left(9,5\right)$.
Thus feasible region has 5 corner points including $\left(7,7\right)$ and $\left(3,3\right)$.