Answer
$\frac{dy}{dx} = -27(4-3x)^{8}$
Work Step by Step
$y = u^{9}$
where,
$u = (4-3x)$
Now,
$\frac{dy}{du} = 9u^{8}$
$\frac{du}{dx} = -3$
So,
$\frac{dy}{dx} = \frac{dy}{du} \times \frac{du}{dx}$
$\frac{dy}{dx} = -27u^{8}$
$\frac{dy}{dx} = -27(4-3x)^{8}$