I've been struggling with this question for a while for some reason, even though it seems much easier that it should be. The question asks for the power dissipated in resistor R (the one in the middle) in terms of R and V. So far I have found the total resistance of the circuit and the current running through the whole circuit, however I am unsure of what to do now. Thanks in advance :)
Total equivalent resistance and total current are,
$$ R_{total} = 2R + \frac{5R \times R}{5R + R} + 3R = \frac{35}{6}R $$ $$ I_{total} = \frac{V}{\frac{35}{6}R} = \frac{6V}{35R} $$
Voltage drop on the middle resistor,
$$ V_R = I_{total} \times \frac{5R}{6} = \frac{V}{7} $$
Power consumption on the middle resistor,
$$ P_R = \frac{V_R^2}{R} = \frac{V^2}{49R} $$
Refer the following equivalent circuit.
