Answer:
a)

b) It will take 11 seconds for the ball to reach the ground.
Step-by-step explanation:
We have an initial height of 880 feet.
And

a) Find s(t), the function giving the height of the ball at time t
The position, or heigth, is the integrative of the velocity. So


In which the constant of integration K is the initial height, so

So

b) How long will the ball take to reach the ground
This is t when

So

This is t = -5 or t = 11.
However, t is the instant of time, so it has to be a positive value.
So it will take 11 seconds for the ball to reach the ground.