A .1 kg piece of aluminum at 90 degrees C is submerged in 1 KG of water at 10 degrees C. What is the temperature when they reach equalibrium? Now I know, aluminum has a c of 920 J/(kg * degree C) and water has a c of 4186 J/(kg * degree C). I'm not sure how to approach this. Best I can think of is setting m*c*dT for the water equal to m*c*dT for the aluminum. But I have two unknown variables there. (The dT's) So that can't be right. Help is appreciated.