Find the final equilibrium temperature when 10.0 g of milk at
10.0(degrees)C is added to 1.60 X 10(squared) g of coffee with a
temperature of 90.0(degrees)C. Assume the specific heats of coffee and
milk are the same as for water  Cp,w =4.19J/ g X C (degrees), and
disregard the heat capacity of the container.

Do a simple heat balance. Assume final templerature T for both milk
and coffee. Now find the amount of heat required to change the
temperatures.