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