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## Homework Statement

The current going through the resistor R1 in the figure does not change whether the two switches S1 and S2 are both open or both closed. The resistances are R1 = 70.00 Ω, R2 = 50.00 Ω, and R3 = 62.00 Ω. The voltage is V = 15 V. With this information, what is the value of the unknown resistance R? Recall that a conducting wire can be treated as a resistor of 0 Ω, and points on a wire between resistors are at the same potential. Hint:

Kirchoff's rules are useful here.

The image is found here: http://www.chegg.com/homework-help/...itches-s1-s2-open-closed-resistances-q4890516

## Homework Equations

R(for series)=R1+R2+R3

R(for parallel)=R1*R2/(R1+R2)

## The Attempt at a Solution

I tried to add up all three resistors originally and got 182 ohms total, then made that equal to 50 + (70R)/(70+R) but it's not working. Not quite sure how to apply Kirchoff's rules here so any help would be appreciated.