Question

The ceramic coffee cup in the following figure (Figure 1), with m = 114 g and c=1090J/(kg⋅K), is initially at room temperature (24.0 ∘C). If 225 g of 80.5 ∘C coffee and 12.4 g of 5.00 ∘C cream are added to the cup, what is the equilibrium temperature of the system? Assume that no thermal energy is exchanged with the surroundings, and that the specific heat of coffee and cream are the same as that of water.