Answer: Our required function F(t) would be

Explanation:
Since we have given that
Let the number of hours be 't'.
Amount for each hour = $6
Let F(t) be the total fee for a single job that took t hours for her to complete.

According to question, for 4 hour job, total fee is $32.
So, it becomes,

Hence, our required function F(t) would be
