Newton's law of cooling

Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its temperature and that of its surroundings. Suppose that the temperature of a cup of coffee obeys Newton's law of cooling. If the coffee has a temperature of 195 degrees Fahrenheit when freshly poured, and 2.5 minutes later has cooled to 185 degrees in a room at 66 degrees, determine when the coffee reaches a temperature of 145 degrees.
The coffee will reach a temperature of 145 degrees in __________ minutes.

Been stuck for awhile

dT/dt = -k(T-S) where T is current temperature and S = ambient temperature
dT/(T-S) = -k.dt
Solving the differential equation gives
ln(T-S) = -kt + C
T-S = e^(-kt+C)
T(t) = S + e^(-kt+C)
T(t) = S +(To-S)*e(-kt) where To = initial temperature at t = 0
T(t) = 66+(195-66)*e^(-kt)
T(t) = 66+129^(-kt)
185=66+129*e^-2.5k
119=129*e^(-2.5k)
ln(119/129) = -2.5k
k = 0.0323
T(t) = 66 + 129*e^(-0.0323t)
145 = 66 + 129*e^-0.0323t)
79/129 = e^(-0.0323t)
ln(79/129) = -0.0323t
t = 15.2 minutes