The circumference of the rectangle, which is the distance travelled in one round = 2(50 m) + 2(20 m) = 100 meters + 40 meters = 140 meters.

Runs around rectangle twice = 2(140 m) = 280 m

Total Distance = 280 meter.

Total Displacement = 0 (because the runner came back to initial point)

Average speed = the distance / time taken 

                         = 280 m / 100 s 

                         = 2.8 m/s

Average velocity = displacement / time taken

                             = 0 / 100 s 

                             = 0.