Question - 
            
            
            
            
            Answer - 
            The feasible region determined by the system of constraints,
isgiven below

O (0, 0), A (4, 0), B (2, 3) and C (0, 4) are the corner pointsof the feasible region
The values of Z at these corner points are given below
   |    Corner  point    |      Z = – 3x +  4y    |    |  
   |    O (0, 0)    |      0    |    |  
   |    A (4, 0)    |      -12    |      Minimum    |  
   |    B (2, 3)    |      6    |    |  
   |    C (0, 4)    |      16    |    |  
Hence, the minimum value of Z is – 12 at the point (4, 0)