V_{B}\cdot{\Big (\frac{1}{R_{1}+R_{2}}+\frac{1}{R_{3}}+\frac{1}{R_{4}+R_{5}}\Big )}=\frac{U_{1}}{R_{1}+R_{2}}+\frac{U_{3}}{R_{3}}+\frac{U_{2}}{R_{4}+R_{5}}