Part A $(100$ Pt$)$

$[20$ Pt$.]$ An optimization programming model is formulated and the constraints thereof are illustrated as follows:

Max. $Z=x+8y$

$s.t.3x+2y,15$

$6x-4y,0$

$y,2$

$9x+6y,20$

$2x-3y,3$

$x,2$

$x,y,0$

The constraints in the model are illustrated in the following plot.

$($a$)$ Pt$.]$ As a linear programing $($LP$)$ model, identify the feasible solution area by its extreme points. $($No need to compute the coordinates$)$

$2$