Three portions of the same liquid are mixed in a container that prevents the exchange of heat with the environment. Portion A has a mass m and a temperature of 96.0 °C, portion B also has a mass m but a temperature of 79.0 °C, and portion C has a mass mC and a temperature of 44.0 °C. What must be the mass of portion C so that the final temperature Tf of the three-portion mixture is Tf = 59.0 °C? Express your answer in terms of m; for example, mc = 2.20 m.