So here you would have to do
distance = time x speed.
distance is 889 meters
time is 15 seconds.
so 889 = 15 x speed
divide 15 on both sides.
889/15
Average speed is 59.2666667 m/s
if it says in the question to round it then just round it.
But whilst checking to see if this answer is correct, i did 59.2666667 multiplied by 15, which equals 889
hope this helped.