The best way to approach these particular problems is to calculate the total amount of calories and divide that by the mass of the final sample. Calories is the amount of energy required to raise the temp of one gram of water by 1 degree Celsius. So the calorie count for the first sample is 100.0 multiplied by 27.0 = 2700 cal and the second sample is 70.3 multiplied by 89.0 = 6256.7. The total calorie count for the final sample is 8956.7 cal, and the total mass of the final sample is 100.0 + 70.3 = 170.3. So the temp is 8956.7/170.3 = 52.59 degrees Celsius. Hope this helps.