Find the temperature of an object when t = 9 if T₀ = 18, C = 5, and k = 0.6.

Newton’s law of cooling says that the rate at which a body cools is proportional to the difference in temperature between the body and an environment into which it is introduced. This leads to an equation where the temperature ƒ(t ) of the body at time t after being introduced into an environment having constant temperature T0 is ƒ(t) = T₀ + Ce^-kt, where C and k are constants.