Calculate the equivalent resistance between P and Q from the following diagram:

Explanation

In the given circuit, two `10Omega` resistances are in series.
`thereforeR_(S)=10Omega+10Omega=20Omega`.
Now, `20Omegaand5Omega` resistances are in parallel.
`therefore1/R_(P)=1/20+1/5`
`1/R_(P)=(1+4)/20=5/20`
`R_(P)=4Omega`
The equivalent resistance between P and Q is given by
`R=3+4+2=9Omega`