|   Basic Variables  |       x1  |       x2  |       x3  |       x4  |       Sign of inequality (Optional)  |       bi  |    
|   −11  |       −19  |       −15  |       0  |       ≤  |       4000  |    |
|   15/4  |       35/4  |       25/4  |       0  |       ≤  |       5000  |    |
|   x4  |       1/40  |       1/40  |       3/40  |       1  |       ≤  |       100  |