So the answers is f(n) = 4n - 1 so how you get it is, f(n) is the output and you are basically working backwards to figure out what fits in to make the answers correct.So what you first you know that n is the input and that is any number to the left.For example let's take 3 so what you do is you multiply 3 by 4 then subtract it by 1 and that gets you to 11.You can do this with any of the inputs and it would still get the same out put if you use that equation.
