1 \cdot k_{12} \cdot x_{1} + 1 \cdot k_{12} \cdot x_{3} + 1 \cdot k_{12} \cdot x_{4} = k_{12} \cdot k_{13}\\ 1 \cdot k_{12} \cdot x_{2} + 1 \cdot k_{12} \cdot x_{3} + 1 \cdot k_{12} \cdot x_{4} + 1 \cdot k_{12} \cdot x_{6} + 1 \cdot k_{12} \cdot x_{11} = k_{12} \cdot k_{14}\\ 1 \cdot k_{12} \cdot x_{4} + 1 \cdot k_{12} \cdot x_{5} + 1 \cdot k_{12} \cdot x_{8} + 1 \cdot k_{12} \cdot x_{9} = k_{12} \cdot k_{15}\\ 1 \cdot k_{12} \cdot x_{7} + 1 \cdot k_{12} \cdot x_{8} = k_{12} \cdot k_{16}\\ 1 \cdot k_{12} \cdot x_{10} + 1 \cdot k_{12} \cdot x_{11} = k_{12} \cdot k_{17}