The corner points of the feasible region in the graphical representation of a linear programming problem are (2, 72) , (15, 20) , and (40, 15) . If z = 18x + 9ʸ is the objective function, then:
a) Maximum value of z is 684 at point (2, 72)
b) Maximum value of z is 855 at point (40, 15)
c) Maximum value of z is 450 at point (15, 20)
d) Minimum value of z is 855 at point (40, 15)
