Stan is about to drink his morning coffee. He pours 400 grams of coffee, initially at 85 degrees Celsius, into a 250 g aluminum cup, initially at 22 degrees Celsius. What is the equilibrium temperature of the coffee-cup system, assuming no heat is lost to the surroundings? The specific heat of aluminum is 900 J/(kg x K), and the specific heat of water is 4186 K/(kg x K).