Let `x` and `y` be the number of desktop and protable computers respectively.
According to the problem,
Maximum profit `Z=4500x+5000y`
and constraints `xge0, yge0`
`x+yle250`
`25000x+40000yle7000000`
`implies25x+40yle7000`
`implies25x+40y le7000`
First, draw the graph of the lines `x+y=250` and `25x+40y=7000`.
Now, find the feasible region from the constraints `xge0,yge0,x+yle250, 25x+40yle7000` and shade it. The vertices of this shaded region are `A(250,0),B(200,50)` and `C(0,175)`. We find the value of `Z` at these vertices.
For the the maximum profit 200 desktop and 50 portable computers should be produced.