Deconstructing Complicated Expressions Practice Test

Which describes the structure of $$4\left(1-\frac{x}{3}\right)^5?$$ (Treat $\left(1-\frac{x}{3}\right)$ as one chunk.)

In the expression $$3a(b+4)^2,$$ interpret it as the product of $a$ and a factor not depending on $a$. Which factor does not depend on $a$?