1. Water with a mass of 0.500 kg at 15 degrees celsius is mixed with 0.800 kg of water at 35 degrees Celsius. What is the final temperature T_f of the mixture? Express your answer in degreesCelsius.

2. In an insulated container, 0.50 kg of water at 80 degrees celsius is mixed with 0.050 kg of ice at -5.0 degrees Celsius. After a while, all the ice melts, leaving only the water. Find the final temperature T_f of the water. The freezing point of water is0 degrees celsius.
Express your answer in degrees Celsius to two significant figures.