Calculate the effective resistance across AB :

Explanation

Given : `5Omega and4Omega` in series
`thereforeR_(1)=(5+4)Omega=9Omega`
Diagram can be simplified as follows :

Now, `9Omegaand3Omega` are in parallel.
`thereforeR_(2)=(9xx3)/(9+3)=27/12=9/4Omega`
Now, `8OmegaandR_(2)` are in series

`thereforeR_(3)=8+9/4=41/4Omega=10.25Omega`