Answer: The speed is 4 meters per second or 4 m/s.
Step-by-step explanation:
First, we have the relationship:
Speed = Distance/Time.
In this case, we know that the fire department arrives to a fire in 210 seconds after leaving the fire station to the burning building which is 840m away, this means that:
Time = 210 seconds
Distance traveled in that time = 840m.
Then the speed is:
Speed = 840m/210s = 4 m/s.
The speed is 4 meters per second.