$(40$ point$)$ Use the graphical method to find all optimal solutions $($Gunakan

metode grafis untuk menemukan semua solusi optimal$)$

Maximize $Z=500x_1+300x_2,$

subject $to$

$15x_1+5x_{2}300$

$10x_1+6x_{2}240$

$8x_1+12x_{2}450$

and

$x_{1}0,x_{2}0.$