Answer:
The answer is C the 2 rectangles
Well, your equation y=3/SQRT(3x+4) should be rationalized, but that's not what you want.
If f(x) = 3/SQRT(x+4) and g(x) = 3x
f(g(x)) then = 3/SQRT(3x+4), but rationalizing this = 3SQRT(3x+4)/(3x+4)
the solution is where the line cross on the y axis, which is on 0
so y = 0