Two spheres, labeled A and B, have identical masses, but are made of different substances. The specific heat capacity of sphere A is 645 J/(kg • C°) and that of sphere B is 240 J/(kg • C°). The spheres are initially at 21 °C; and the same quantity of heat is added to each sphere. If the final temperature of sphere A is 74 °C, what is the approximate final temperature of sphere B?