1. Each machine can be assigned to only one product. Set up the objective function and the constraints necessary to minimize the total time.

\begin{tabular}{||l||l|l|l||} \hline \multicolumn{1}{|l||}{} & \multicolumn{3}{|c|}{ Product } \\ \hline \hline Machine & A & B & C \\ \hline 1 & 11 & 12 & 10 \\ \hline 2 & 12 & 9 & 11 \\ \hline 3 & 13 & 15 & 12 \\ \hline \end{tabular} Each machine can be assigned to only one product. Set up the objective function and the constraints necessary to minimize the total time