Linear maximization problem

Objective: 1.5*x1 + 2.5*x2 + 3*x3 + 4.5*x4

Constraints: 
C1: 2*x1 + 4*x2 + 3*x3 + 7*x4 <= 100000
C2: 3*x1 + 2*x2 + 3*x3 + 4*x4 <= 50000
C3: 2*x1 + 3*x2 + 2*x3 + 5*x4 <= 60000
C4: x1 >= 0
C5: x2 >= 0
C6: x3 >= 0
C7: x4 >= 0

Report: 

                                            Allowable    Allowable
Variable      Final Value   Reduced Cost    Increase     Decrease
  x1                  0             0        1e+030           1.5
  x2              16000             0      0.142857             2
  x3               6000             0           0.5          0.75
  x4                  0             0        1e+030           0.2

                                            Allowable    Allowable
Constraint    Shadow Price       Slack      Increase     Decrease
  C1                  0        -18000        1e+030         18000
  C2               -0.8             0         40000         10000
  C3               -0.3 -7.27596e-012         15000       26666.7
  C4                1.5             0          6000         18000
  C5                  0         16000         16000        1e+030
  C6                  0          6000          6000        1e+030
  C7                0.2             0       11428.6        1e+030