Answer:
The price per share after 4 hours is $21.43
The price per share after 20 hours is $4.15
Explanation:
Equations
The price of the company's stock is initially at $25.75 per share. Each hour the price drops by $1.08. This condition can be modeled by the function:

Where t is the time in hours.
The sign means the function is decreasing as time passes.
When t=4 hours, the price will be:

The price per share after 4 hours is $21.43
Now find the price when t=20 hours

The price per share after 20 hours is $4.15