Implicit differentiation and inverse trigonometric functions practice question 2

The arcsin here is applied to $x/3$, not to $x$. Which standard derivative do you need, and what extra factor does the inside bring?

$\dfrac{d}{dx}\arcsin u = \dfrac{u'}{\sqrt{1 - u^{2}}}$. Here $u = x/3$, so $u' = 1/3$, and at $x = \tfrac{3}{2}$ the inside is $u = \tfrac{1}{2}$.