Answer:
a)

b)

Explanation:
a)
Let
= height above ground
Let
= time
Because the bird descended down to 250 feet in 10 seconds with a steady rate, that means it descends 25 feet per second.
∴

b)
To find the time it takes until the bird reaches the ground,
must equal
:



∴ It takes 20 seconds for the bird to reach the ground.