The corner points of the bounded feasible region are: (5,5), (15,15), (0,20), and (0,10).
The objective function is z=3x+9y.
In Linear Programming, the maximum and minimum values of the objective function occur at the corner points of the feasible region.
At point (5,5):
z=3(5)+9(5)
z=15+45
z=60
At point (15,15):
z=3(15)+9(15)
z=45+135
z=180
At point (0,20):
z=3(0)+9(20)
z=0+180
z=180
At point (0,10):
z=3(0)+9(10)
z=0+90
z=90
The values of z are: 60,180,180,90
Maximum value of z=180
Minimum value of z=60
maximum(z)−minimum(z)=180−60
=120
Therefore, the value of maximum(z)−minimum(z)=120