Answer:
Input = 5
Explanation:
Output = Answer a.k.a. f(x)
Input = x
We start by replacing f(x) with the output, which is 11
11 = 4x-9. I like making it opposite. It's easier in my eyes.
Making it opposite it's 4x-9 = 11
Now we need to get x by itself. The opposite of -9 is +9. So if we add 9 to each side, it deletes the 9 from the left and puts it on the other side, making it;
4x = 11 + 9. 11 + 9 is 20, so....
4x = 20.
Now 4x is the same as 4 times x. The opposite of times is divide. So let's divide by 4 on both sides. That gets rid of the 4 on the left side and puts it on the other side, making it;
x = 20/4. 20/4 is 5, so...
x = 5