\frac{dx_{1}}{dt} = 1 \cdot k_{15} \cdot 1 / 4 \cdot \left(1 - x_{3} - x_{1}\right) / k_{15}\\
\frac{dx_{2}}{dt} = 1 \cdot k_{15} \cdot \left(6 \cdot x_{1} / \left(1 + 2 \cdot x_{1}\right) \cdot \left(1 - x_{2}\right) / \left(k_{14} + 1 - x_{2}\right) - 3 / 2 \cdot x_{2} / \left(k_{14} + x_{2}\right)\right) / k_{15}\\
\frac{dx_{3}}{dt} = 1 \cdot k_{15} \cdot \left(x_{2} \cdot \left(1 - x_{3}\right) / \left(k_{14} + 1 - x_{3}\right) - 7 / 10 \cdot x_{3} / \left(k_{14} + x_{3}\right)\right) / k_{15}