The corner points of the feasible region are (0,0), (0,40), (20,40), (60,20), (60,0).
The objective function is z=4x+3y.
In linear programming, the maximum or minimum value of the objective function occurs at one of the corner points of the feasible region.
At point (0,0):
z=4(0)+3(0)
z=0
At point (0,40):
z=4(0)+3(40)
z=0+120
z=120
At point (20,40):
z=4(20)+3(40)
z=80+120
z=200
At point (60,20):
z=4(60)+3(20)
z=240+60
z=300
At point (60,0):
z=4(60)+3(0)
z=240+0
z=240
Comparing all values:
At (0,0): z=0
At (0,40): z=120
At (20,40): z=200
At (60,20): z=300
At (60,0): z=240
The maximum value of z=300 occurs at point (60,20).