Graphical Method Show All Work

a$.$ MaxZ$=30x15y$

s$.$t$.$

$-2x-y-20$

$x7$

$x-y10$

$x0,y0$

$c.$ MinZ$=10x_{1}7x_2$

$s.t.$

$,5x_{1}6x_{2}420$

$x_{1}60$

$x_{2}45$

$x_1,x_{2}0$

b$.$ MinZ$=2x5y$ s$.$t$.$

$xy2$

$x5$

$y4$

$,x0,y0$

d$.$ MaxZ$=2x5y$ s$.$t$.$

$3x-2y6$

$5x-4y8$

$xy$

$x0,y0$

Help me understand and solve this please