This question is a little tricky. They worded it to trick you. But you just have to remember that whatever f(x) is equal to that is your x for g(x). So we are going to solve f(x).
Since we know that f(x) is equal to 4x, we want to know what f(-2) is. So we are going to substitute -2 for x. Our new equation would be f(-2)=4(-2). We know that a negative number time a positive number is going to be negative. So our answer is f(-2)=-8. But wait, we are not done.
Now we are going to substitute -8 in for x on g(x). We know that g(x) is equal to 2x-1. So we have a new equation. g(-8)=2x-1. We are going to substitute -8 for x. And we get g(-8)=2(-8)-1. Now as I said last time a negative times a positive is a negative.
But we have three numbers here, how will we know what to do. The Acronym PEMDAS will help us. PEMDAS stands for Parenthesis, Exponents, Multiplication Division, Addition Subtraction. We need to look in our equation and see if we have parenthesis or exponents. I don't see any, that aren't separating a negative from a positive. So we go on to multiplication and division. I see a multiplication. g(-8)=2(-8)-1. So we are going to multiply 2 and -8. Our new equation is gonna be g(-8)=-16-1. Our next step is Addition or Subtraction. We are going to subtract 1 from -16. But wait. The subtraction sign in front of the 1 tells me that it is negative, and if we subtract a negative from a negative we are adding 1. So our final equation is gonna be g(-8)=-17.
I hope this helps. If you need any additional help with this problem or future problems just ask.