Answer
$5$ radians/sec
Work Step by Step
Here, $\dfrac{ds}{dt}=r\dfrac{d\theta}{dt}$
Plug $\dfrac{ds}{dt}=6; r=1.2$
Then , we have
$\dfrac{ds}{dt}=r\dfrac{d\theta}{dt}$
This implies that
$\dfrac{d\theta}{dt}=\dfrac{6}{1.2}=5$ radians/sec