free coffee for smart people tuesday

alright, fellow nerds...
here's the third installment of free coffee for smart people tuesdays trivia question. as always, you have two weeks to enter any brew nerds location, both on earth and in outer space. inform the coffee specialist of the answer and he or she will reward you with a savory beverage selection of your choice. in the 450 milliliter size, that is.

here's a practical question:

your barista hands you your cup of coffee and it's 140° F. ten minutes later, you remove your thermometer from your pocket protector and measure and it's now 120° F.
assuming exponential decay in temperature (who wouldn't?) and that room temperature is 70°, what will the temperature be in 20 more minutes, 30 minutes from when it was handed to you?

you may begin.... now.