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Question
Solve the following LPP graphically :
Maximise Z = 105x + 90y
subject to the constraints
x + y ≤ 50
2x + y ≤ 80
x ≥ 0, y ≥ 0.
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Solution
The given equations are
x + y ≤ 50
2x + y ≤ 80
x ≥ 0, y ≥ 0
First convert the inequations into equations to obtain the lines
x + y = 50
2x + y = 80
x = 0, y = 0
Line x + y = 50 meets the coordinate axes at points A(0, 50) and E(50, 0). Join these points to make the line x + y = 50.
Similarly, line 2x + y = 80 meets the coordinate axes at points B(0, 80) and D(40, 0). Join these two points to make the line 2x + y = 80.
Lines 2x + y = 80 and x + y = 50 meet each other at C(30, 20).
The coordinates of the corner points are O(0, 0), A(0, 50), C(30, 20) and D(40, 0).

We have to maximize Z = 105x + 90y. So, we will find the corner point where the value of Z is maximum.
| Corner Points | Corresponding value of Z |
| O(0, 0) | 0 |
| A(0, 50) | 4500 |
| C(30, 20) | 4950 |
| D(40, 0) | 4200 |
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