# On bridges

For the Wheatstone bridge above, let $$R = \frac {391}{13}\:\Omega,\: R_2 = 252\:\Omega,\: R_4 = 120\:\Omega,\: V_{EX} = 5\: V$$ dc. If $$V_O = 0 \: V$$, and the voltage drop across $$R$$ is $$\frac {1955}{2743} \: V$$, determine the sum (in ohms) of the resistances $$R_1$$ and $$R_3$$.

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