Tf should be 27.9C, please show full steps! thanks!

Example 1-1: What is the final temperature of the system when 0.500g of H2O(I), initially at 20C, is mixed with 0.750g of Cu(s) initially at 85C ? Assume all processes occur at constant pressure. \begin{tabular}{|l|c|} \hline Substance & Cp/JK1mol1 \\ at room temperature \end{tabular}