Equation for the horizontal asymptote.

[arroww]

How would you find the equation for the horizontal asymptote of the following exponential function?:
$$g(x) = -2f(2x - 6)$$

Let $$f(x) = 4^x$$

 

[MarkFL]

I would begin by looking at the horizontal asymptote of $f$...can you see what this is?