18.17 Mathematical methods and models in economics

\( \underline{\mathrm{y}_{\text {word: }}} \) Let the balance sheet for the three-branch economic model have the form: \begin{tabular}{|c|c|c|c|c|} \hline \multirow{2}{*}{\( \begin{array}{c}\text { Number } \\ \text { producing } \\ \text { industry }\end{array} \)} & \( \begin{array}{c}\text { Gross output } \\ \text { products in } \\ \text { industry }\end{array} \) & \multicolumn{2}{|c|}{ Products consumed in the industry } \\ \cline { 3 - 5 } & 300 & 1 & 2 & 3 \\ \hline 1 & 200 & 40 & 30 & \( a \) \\ \hline 2 & 250 & \( b \) & 50 & 60 \\ \hline 3 & 20 & \( c \) & 100 \\ \hline\end{ta