I put a cup of hot coffee in my room The temperature T at ti

I put a cup of hot coffee in my room. The temperature T at time t ( in hours) is

T=60+40e^-2t

a) How warm is the Coffee right now?

b)What will the temperature be in 2 hours?

c) How long does it take the coffee to cool to 50 degrees?

a)
T=60+40*e^-2t
put t= 0
T = 60+40*e(-2*0)
= 60 + 40*1
= 100 degree

b)
T=60+40*e^-2t
put t= 2
T = 60+40*e(-2*2)
= 60 + 40*0.0183
= 60.73 degree

c)
T=60+40*e^-2t
put T = 50
50 = 60+40*e(-2*t)
- 10 = 40*e(-2*t)
-0.25 = e(-2*t)
It is not possible

It will never cool to 50 degree