While studying for this quiz you realize that you still have 100 g of lukewarm coffee at 40°C left in a paper cup. When you pour 50 g of boiling water into the cup, the temperature of the resulting coffee-like mixture will now be??

Answer 1

heat in = heat out
100 (T-40) = 50 (100-T)
2 T - 80 = 100 - T
3 T = 180