Determine the row and column of the next pivot value based on the following simplex tableau. \begin{tabular}{|c|c|c|c|c|c|c|c|c|} \hlinex1 & x2 & x3 & x4 & s1 & s2 & s3 & z & \\ \hline 1 & 3 & 4 & 3 & 1 & 0 & 0 & 0 & 80 \\ \hline 1 & 4 & 2 & 5 & 0 & 1 & 0 & 0 & 70 \\ \hline 3 & 1 & 4 & 2 & 0 & 0 & 1 & 0 & 120 \\ \hline-6 & -5 & -10 & -2 & 0 & 0 & 0 & 1 & 0 \\ \hline \end{tabular}