Question 1:
The length of EC is not needed.
According to the Mid segment Theorem, just multiply the length of DF by 2 to get the length of AC.
You get 32.
Question 2:
We know that n+9 and 4n-6 are equal to each other because DF is a bisector.
4n-6 = n+9
Subtract both sides by n
3n - 6 = 9
Add both sides by 6
3n = 15
n = 5
Plug this value into 4n-6 or n+9
You get 14 for both.
14 is your answer.
Have an awesome day! :)