F(x)=3x-8

6x

find and simplify

f(3)-f(1)

3-1

i have no idea what this question is, any ideas?

What this is asking is for you to plug values into the following function:

Since the question is asking you to find , this is how you work it out:
You take the function;

And plug the numbers indicated in for x;

So the answer to f(3) - f(1) =

Think of it as five or above give it a shove. change the 5 or above to the right to a zero and add one to the number on the left.

The correct answer is d, hope this