Ok 1st step - you use the intersecting chords theorem, which states that when two chords intersect in a circle, the product of the lengths of the segments on one chord is equal to the product of the lengths of the segment on the other chord. In this case, |AP|⋅|PB|=|CP|⋅|PD|
3⋅|BP|=2⋅6=12 , so |BP| = 4