The average cooling time of a hot cup of coffee

Wonder how much longer a cup of hot coffee takes to cool down when it 30 degrees(or in my case only 29,7) compare to the average Danish office temperature which I guess is around 21 degress.

Many strange questions pass through the tired brain. Maybe the question is all wrong? Maybe the proper questions is; why anybody wants to drink hot coffee when its this hot? And why is it that coffee from all machines taste terrible? In a world full of injustice it seems like a unfair thing to complain about, but still, it could be nice to have a hot cup of coffee, a cold place.

But in the end the coffee did what it should, it woke me up a bit.