$($Could you please explain the basic equations while working through the problem.$)$

Pin $P$ is attached to the wheel shown and slides in a slot cut in bar $BD.$ The wheel rolls to the right without slipping with a constant angular velocity of $20ra\frac{d}{s}.$ Knowing that $x=480mm$ when $=0,$ determine the angular velocity of the bar and the relative velocity of pin $P$ with respect to the rod when

$($a$)=0$

$($b$)=90$

Figure $5$ : Question $5$