Motion in a plane

The position of a particle is given by
ˆ ˆ ˆ 2 r i j k = − + 3.0 2.0 4.0 m t t
where t is in seconds and the coefficients have the proper units for r to be in metres.
(a) Find the v and a of the particle? (b) What is the magnitude and direction of
velocity of the particle at t = 2.0 s ?