Question 884228
I think you may have left something out of the function. Maybe F(x) = -3x +1 or something.

But in any case, think of F(x) as what you are trying to find. You do not know what it is. You are told the function in terms of x. 

So you plug in an x, and then calculate the F(x)

Would it be easier to say {{{y = -3x +1}}} ??? 
Could you plot that?

{{{graph (300, 200, -10, 10, -10, 10, -3x+1)}}}