electric circuit!!!!!urgent!!!

If you re-draw the circuit, it becomes (2 resistors in parallel) in series with another (2 resistors in parallel). This arrangement is then in parallel with a single resistor.

Hence, equivalent resistance of 2 resistors in parallel
= 12/2 ohms = 6 ohms

Equivalent resistance of two "6-ohm" resistance in series = 12 ohms
Equivalent resistance of the whole circuit
= 12/2 ohms = 6 ohms

http://upload.lsforum.net/users/public/f38451RW343j84.bmp

For reference only^^