An importer of Brazilian coffee estimates that local consumers buy approximated d= 1984/p^2 kilograms of coffee per week when the price is p dollars per kilogram. It is also estimated that t weeks from now, the price of Brazilian coffee will be p=0.05t^2 +0.2t +13 dollars per kilogram. At what rate will the weekly demand for coffee be changing with respect to time 10 weeks from now?