Respuesta :

The dragonfly can fly faster by 4.5 feet per second

The butterfly's speed is 20.5 feet per second 
The dragonfly's speed is 25 feet per second

the average speed of butterfly is 20.5 ft/s
[tex] \frac{82}{4} = 20.5[/tex]

the average speed of dragonfly is 25ft/s
[tex] \frac{50}{2} = 25[/tex]

so the difference is
[tex]25 - 20.5 = 4.5[/tex]
the dragonfly can fly faster 4.5 ft more in a second.

good luck