x_{10} = x_{1} + x_{3}\\ x_{11} = x_{2} + x_{4}\\ x_{12} = x_{8} + x_{3} + x_{4}\\ x_{15} = x_{13} + x_{14}\\ x_{16} = x_{7} + x_{13} + x_{14}\\ x_{17} = x_{9} + x_{13}\\ x_{18} = x_{9} + x_{6} + x_{13} + x_{14}\\ 1 \cdot k_{27} \cdot x_{6} + 1 \cdot k_{27} \cdot x_{9} + 1 \cdot k_{27} \cdot x_{13} + 1 \cdot k_{27} \cdot x_{14} = k_{27} \cdot k_{28}