<h3><u>Answer</u> :</h3>
First of all see the attachment for better understanding
:D
<u>Eq. resistance between C and D</u> :
➝ 1/Rp = 1/6 + 1/6
➝ 1/Rp = 2/6
➝ <u>Rp = 3Ω</u>
<u>E</u><u>q. resistance of upper part </u>:
(All three are in series)
➝ Rs = 3 + 3 + 3
➝ <u>Rs = </u><u>9</u><u>Ω</u>
<u>Eq. resistance of lower part</u> :
(Both are in series)
➝ Rs' = 3 + 3
➝ <u>Rs' = 6Ω</u>
<u>Eq. resistance between A and B </u>:
(Rs and Rs' are in parallel)
➝ 1/Req = 1/Rs + 1/Rs'
➝ 1/Req = 1/9 + 1/6
➝ 1/Req = (2 + 3)/18
➝ Req = 18/5
<h3>➝
<u>Req = </u><u>3</u><u>.</u><u>6</u><u>Ω</u></h3>