\frac{dx_{1}}{dt} = \left(1 \cdot k_{14} \cdot k_{1} \cdot x_{5} + 1 \cdot k_{14} \cdot k_{2} \cdot k_{15} + -1 \cdot k_{14} \cdot k_{3} \cdot x_{1} + -1 \cdot k_{14} \cdot k_{4} \cdot x_{1} \cdot x_{2}\right) / k_{14}\\ \frac{dx_{2}}{dt} = \left(1 \cdot k_{14} \cdot k_{9} \cdot x_{1} + -1 \cdot k_{14} \cdot k_{10} \cdot x_{2}\right) / k_{14}\\ \frac{dx_{3}}{dt} = 0