1. The problem statement, all variables and given/known data I have been stuck at the following question for some time now. All help is appreciated. 2. Relevant equations P=IV, V=IR 3. The attempt at a solution I have resolved the right side of the circuit into a 10 ohm resistor. I have also found the current in the 20 ohm resistor (0.4A). I then used Ohm's Law to get the current in the 10 ohm resolved resistor and found it to be 5A. Then using Kirchoff's Current Law, I got 5.4A in the unknown resistor R, which gives a resistance of 9.26 ohms. This 9.26 ohms however disagrees with the given answer of 10 ohms. Where have I went wrong? All help is appreciated! Thanks!