Suppose the demand function for a product is given by $$D(p)=\frac{100000}{p}$$ where $D(p)$ is the quantity in demand at price $p$. Also suppose that price is a function of time: $$p=4.5 t+12$$ where $t$ is in days.

Find the rate of change of the quantity in demand after 84 days.

units per day

Round to three decimal places.