There is a total of 400 possible points so you are going to want to find 20% of that 400 points. To find that 20% you have to multiply 20×400=8000 THEN you want to divide that by 100 ( because that is the total possible percent and you get 80.
F(4) value is 6. I believe it would work like this: f(x) is being turned into f(4), so 4 would equal x. Put 4 into the equation 3x-6, and you get 12-6, which gives you 6. So the value of f(4) is 6. I hope this helps!
