Newton's law of cooling is sometimes called "Convection-cooling" is independent of the temperature difference between object and environment.
T2 = T0 + (T1 - T0) * e(-k * Δt)
where:
k: Constant to be found
Δt: Time difference of T2 and T1
T1: Initial Temperature
T2: Final Temperature
T0: Constant Temperature of the surroundings
For example, when Time is 9, surrounding temperature is 20, initial temperature is 30, Core temperature is 32, then Temperature of the object at time t T(t) is 72.