I do K12 7th grade and it has really brought my grades up! One thing I have noticed though is the work is more advanced then the work at a normal school. At first I had alot of trouble getting used to the system but after awhile it's very simple. I really like K12 because it let's you learn at your own pace. if you have any questions about K12 I would be happy to answer.
The correct answer is letter F
Answer:

Step-by-step explanation:
I am assuming that you are asking what is [x] - 5 if f(86).
When you have this kind of question, what you do is to substitute the variable inside the parenthesis, so like what is says, f(x). If the question replaces the variable x with 86, that means you input the number into the equation.
So [x] - 5, if f(86).
Substitute:
86 - 5

Answer:
a.
Step-by-step explanation:
x=4
3(2)=6
6(4)=24
24 is your answer!
Answer:
C
Step-by-step explanation:
5.-10.20.-40.80.-160.320
This pattern shows each number being multiplied by -2