No math is needed to explain this. All that you need to know is that the can (4°C) is in your hand (37°C).
Entropy will always move toward being balanced. Never will you find a lake in which half of it is 1°C and the other half is 70°C; it will be equal throughout.
Remember that "cold" doesn't exist. What we describe to be cold is actually a lack of heat.
So, by applying the two ideas above, it can be concluded that:
Since your hand is warmer than the can, the heat from your hand will be transferred to the can in order to reach an equal temperature.
