x_{5} = x_{4} + x_{3} + x_{2}\\
1 \cdot k_{72} \cdot x_{1} + 1 \cdot k_{72} \cdot x_{2} + 1 \cdot k_{72} \cdot x_{3} + 1 \cdot k_{72} \cdot x_{4} = k_{72} \cdot k_{73}