Three resistors 5$\Omega$, 10 $\Omega$ and 4$\Omega$ are connected as shown in the figure.  The equivalent resistance between the points A and b is

$\frac{20}{11}\Omega$

Point A and C are at the same potential and Point B and D are at the same potential.

All the three resistors are in parallel.

$ \frac{1}{R} = \frac{1}{5} +\frac{1}{10} + \frac{1}{4} = \frac{11}{20}$

$ R = \frac{20}{11} \Omega$