Current in a resistor and potential difference

[tag16]

Homework Statement

In the circuit of figure p28.23, determine the current in each resistor and the potential difference across the 200 ohms resistor.

http://s848.photobucket.com/albums/ab41/tag16/?action=view&current=circuit.jpg&newest=1

Homework Equations

1/Req= 1/R1+1/R2+1/R3+1/R4
I=deltaV/R
deltaV= IR

The Attempt at a Solution

Req=1/(1/200ohms +1/80ohms+ 1/20ohms+ 1/70ohms)= 12.22 ohms

I=-240V/12.22ohms= -19.6 A
deltaV= (-19.6A)(12.22)= -239 V
Am I doing this completely wrong? If so what do I need to do?

 

[rl.bhat]

To solve this problem, you must know network theorems. Some of them are Kirchhoff law, source conversion method, etc.