Respuesta :
Answer: The answer is 4...
Explanation: this is a simple equation if you're trying to find X and f(x) = 12 but A(x) equals 3x your basically doing 3 times what equals 12 which in this case that would be 4 (well in any case it would be 4) I know this is confusing so hear me out (sorry)
f(x) = 12
A(x) = 3x
3 x 4 = 12
x = 4
Like I said sorry if this makes you confused but the answer is 4 :)
brainliest? (even though I'm two weeks late)