algebra precalculus - Find consumer demand as a function of time, given the demand equation and price

An importer of Brazilian coffee estimates that local consumers will buy approximately $Q(p)= 4374/p^2$ kg of the coffee per week when the price is $p$ dollars per kg. It is estimated that $t$ weeks from now the price of this coffee will be $p(t) = 0.04t^2 + 0.2t + 12$ dollar per kg.

a) Express the weekly consumer demand for the coffee as a function of $t$.

b) How many kg of the coffee will consumers be buying from the importer $10$ weeks from now?

c) When will the demand for the coffee be $30.375$ kg?

Here's my solution
a)
$$\begin{align*} q(p) & = \frac{4374}{p^2} p^{-2}\\ & = 4374 -2 p^{-3}\\ & = \frac{4372}{p^3} \end{align*}$$
and I don't really know how please help me