Answer:There are several ways to calculate this.
The easiest way would be to determine the distance the bird flew.
40km/h x 4h = 160km
30km/h x 2,5h= 75km
Then add up the total distance: 160km + 75km = 235km
Next add up the total time: 4h + 2,5h = 6,5h
So in total the bird flew 235km in 6,5h. Now just divide both numbers by 6,5 as what you want to know is how far the bird got during an average hour.
Explanation: