A mug of tea has been left to cool from 90C to 18C. If there is 0.

A mug of tea has been left to cool from 90°C to 18°C. If there is 0.2 kg of tea in the mug, and the tea has a specific heat capacity 4200 J K^−1 kg^-1, show that the entropy of the tea has decreased by 185.7 JK^-1. Comment on the sign of this result.