Determine the correct pivot element for the following simplex tableau.

$$\displaystyle\left[\begin{array}{rrrrrrr|r} P&x_1&x_2&x_3&s_1&s_2&s_3&\scriptscriptstyle\text{RHS}\cr0 &1 &12 &0 &20 &-15 &0 &39 \cr 0 &0 &-13 &0 &-15 &9 &1 &66 \cr 0 &0 &6 &1 &-12 &0 &0 &77 \cr \hline 1 &0 &-12 &0 &-3 &-8 &0 &57 \cr \end{array}\right]$$

Pivot row number (1, 2, 3, or 4) =
Pivot column number (1, 2, ... or 8) =