\frac{dx_{10}}{dt} = 0\\
\frac{dx_{11}}{dt} = 0\\
\frac{dx_{12}}{dt} = 0\\
\frac{dx_{1}}{dt} = k_{1} \cdot x_{7} \cdot x_{2} / \left(k_{8} + x_{2}\right) - k_{2} \cdot x_{1} / \left(k_{8} + x_{1}\right)\\
\frac{dx_{3}}{dt} = \left(k_{5} + x_{3}\right) \cdot x_{4} / \left(k_{9} + x_{4}\right) - k_{4} \cdot x_{1} \cdot x_{3} / \left(k_{9} + x_{3}\right) - k_{7} \cdot x_{3} \cdot x_{5} / \left(k_{9} + x_{3}\right)\\
\frac{dx_{5}}{dt} = k_{6} \cdot x_{7} \cdot x_{6} / \left(k_{9} + x_{6}\right) - k_{3} \cdot x_{3} \cdot x_{5} / \left(k_{9} + x_{5}\right)\\
\frac{dx_{8}}{dt} = \left(-x_{8}\right) \cdot \frac{1}{5}\\
\frac{dx_{9}}{dt} = \left(-x_{9}\right) \cdot \frac{1}{2}