Answer:
Average Speed = Total Distance / Total Time
In this case, Luca runs 75 meters east and then 55 meters east, so the total distance is 75 + 55 = 130 meters. The total time is 100 seconds for the first part and 225 seconds for the second part, so the total time is 100 + 225 = 325 seconds.
Average Speed = 130 meters / 325 seconds
Average Speed = 0.4 meters per second
soo Luca's average speed is 0.4 meters per second.