In an experiment, a student releases 10 pieces of one-dollar coins heated to 140 °C into a thermally insulating container of mass 50 g and specific heat capacity 420 J/kg•°C. The container is filled with a mixture of ice (5 g) and water (200 g) at the same temperature. Each coin has a specific heat of 390 J/kg•°C and a mass of 8.1 g. Determine the final temperature (T). Assume that the container does not allow heat exchange with surroundings.