Linear Velocity of a Point That Is Fixed Within a Rotating Reference Frame

Equation 60 from page=16 The velocity of point $P$ relative to the origin of the inertial reference frame is

$${\vec{v}}_{P/0}={\vec{v}}_b+\frac{d}{dt}({\vec{r}}_{P/b})={\vec{v}}_b+\vec{\omega }\times {\vec{r}}_{P/b}$$