\frac{dx_{1}}{dt} = \left(1 \cdot k_{20} \cdot k_{2} \cdot k_{3}^{k_{4}} / \left(k_{3}^{k_{4}} + x_{3}^{k_{4}}\right) + -1 \cdot k_{20} \cdot k_{5} \cdot x_{1} / \left(k_{6} + x_{1}\right) + 1 \cdot k_{20} \cdot k_{7} \cdot k_{8} \cdot 1 / 2 \cdot \left(x_{4} + x_{8}\right) / \left(k_{9} + k_{8} \cdot 1 / 2 \cdot \left(x_{4} + x_{8}\right)\right) + 1 \cdot k_{20} \cdot k_{10}\right) / k_{20}\\
\frac{dx_{2}}{dt} = \left(1 \cdot k_{20} \cdot k_{11} \cdot x_{1} + -1 \cdot k_{20} \cdot k_{12} \cdot x_{2} / \left(k_{13} + x_{2}\right)\right) / k_{20}\\
\frac{dx_{3}}{dt} = \left(1 \cdot k_{20} \cdot k_{14} \cdot x_{2} + -1 \cdot k_{20} \cdot k_{15} \cdot x_{3} / \left(k_{16} + x_{3}\right)\right) / k_{20}\\
\frac{dx_{4}}{dt} = \left(1 \cdot k_{20} \cdot k_{17} \cdot x_{1} + -1 \cdot k_{20} \cdot k_{18} \cdot x_{4} / \left(k_{19} + x_{4}\right)\right) / k_{20}\\
\frac{dx_{5}}{dt} = \left(1 \cdot k_{20} \cdot k_{2} \cdot k_{3}^{k_{4}} / \left(k_{3}^{k_{4}} + x_{7}^{k_{4}}\right) + -1 \cdot k_{20} \cdot k_{5} \cdot x_{5} / \left(k_{6} + x_{5}\right) + 1 \cdot k_{20} \cdot k_{7} \cdot k_{8} \cdot 1 / 2 \cdot \left(x_{4} + x_{8}\right) / \left(k_{9} + k_{8} \cdot 1 / 2 \cdot \left(x_{4} + x_{8}\right)\right) + 1 \cdot k_{20} \cdot k_{10}\right) / k_{20}\\
\frac{dx_{6}}{dt} = \left(1 \cdot k_{20} \cdot k_{11} \cdot x_{5} + -1 \cdot k_{20} \cdot k_{12} \cdot x_{6} / \left(k_{13} + x_{6}\right)\right) / k_{20}\\
\frac{dx_{7}}{dt} = \left(1 \cdot k_{20} \cdot k_{14} \cdot x_{6} + -1 \cdot k_{20} \cdot k_{15} \cdot x_{7} / \left(k_{16} + x_{7}\right)\right) / k_{20}\\
\frac{dx_{8}}{dt} = \left(1 \cdot k_{20} \cdot k_{17} \cdot x_{5} + -1 \cdot k_{20} \cdot k_{18} \cdot x_{8} / \left(k_{19} + x_{8}\right)\right) / k_{20}