 If there is more than one row for which the minimum is achieved then a "dropping variable choice rule" can be used to make the determination.Consider the linear program

With the addition of slack variables "s" and "t", this is represented by the canonical tableau

where columns 5 and 6 represent the basic variables "s" and "t" and the corresponding basic feasible solution is 

Columns 2, 3, and 4 can be selected as pivot columns, for this example column 4 is selected.The values of "z" resulting from the choice of rows 2 and 3 as pivot rows are 10/1 = 10 and 15/3 = 5 respectively.