Answer:
D. 32
Step-by-step explanation:
For this problem, we simply plug -9 in for x in f(x):
⇒ 
Thus, the answer is D. 32.
Hope this helps!
5x + 10 10
---------- = -------
121 11
make the bottom have same common denominator
10/11 x (10/10) = 100/121
Get rid of the denominator (for both now have 121 as a base)
5x + 10 = 100
5x + 10 (-10) = 100 (-10)
5x = 90
5x/5 = 90/5
x = 18
x = 18 is your answer
hope this helps
In the attachment is a graph of the cosine function that represents changing of the tide.
y max = 10 ft at midnight
y min = 5 ft at 6 AM