If the velocity of a body changes from 13m/s to 30m/s while undergoing constant acceleration, what's the average velocity of the body?

       Average speed = (1/2) (beginning speed + ending speed)

                               = (1/2)        ( 13 m/s  +  30 m/s )

                               =    (1/2)        ( 43 m/s )

                               =        21.5 m/s