From the figure, find the value of $\angle$COB.

The correct option is B 60°
From the figure, AOB is a straight line.
Hence,
$\angle$ AOC + $\angle$ COB = 180° (Linear pair)
$\Rightarrow$ 4x° + 2x° = 180°
$\Rightarrow$ 6x° = 180°
$\Rightarrow x°=\frac{180°}{6}=30°$
Then, $\angle$ COB = 2x° = 2$\times$ 30° = 60°.