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