Could someone explain to me how to got the answer B, thank you very much​

since -6 lasted for 5 seconds, multiplying both would result in -30

3 lasted for 10 seconds, so multiplying both would give +30

average = ( 30 + (-30) ) / 2

30 -30 is already equal to zero, so the answer should be 0

i think it's 35 meters

answer; how far out of place which the object finished relative to the starting location;