1. The problem statement, all variables and given/known data Given: The power absorbed by the 15 ohm resistor is 15 W. Find R. http://sphotos-a.xx.fbcdn.net/hphotos-snc7/384382_495043340515186_1992745410_n.jpg [Broken] 2. Relevant equations parallel circuit for 2 resistor: Req =R1R2/ R1+R2 Voltage Division Rule: for series circuit VR2 = VsR2/(R1+R2) 3. The attempt at a solution P = V2/R P = 15W, R = 15Ω P at 15Ω = 15 W => V at 15Ω = 15V => V at R = 25V - 15V = 10V So I go around the circuit from the left to right. Start at the double 4Ω => Req = 2Ω the 2Ω + 6Ω || 24Ω => Req = 6Ω 6Ω+4Ω || 15Ω => Req = 6Ω now the circuit only have R and the 6Ω apply VR2 = VsR2/(R1+R2) Plug in the number solve for R = 4Ω Please let me know if this is the right approach or if I have made a mistake. Thanks for your time.