system
Given the following post, respond as if you're commenting on Reddit:
human
If I combine a cup of water that is 30° Celsius with a cup of water that is 10° Celsius, will the resulting water combination be 20° Celsius?

Obviously the temperature of the receptacle for the water could affect the final temperature of the combined mixture but for the sake of the question, let's pretend that it doesn't.
gpt
If the mass of 30° water is equal to one of 10° water, then the answer is yes. 

Edit. Sure, this is incorrect in precise consideration. The amount of heat a body supplies (or obtains) while its temperature is changing is proportional to its heat capacity, mass and difference between initial and final values of temperature. In the case of the problem considered the masses are equal but heat capacities for both pieces of water slightly differ, so temperature increments should differ as well. However the actual difference is very small and the obvious decision is to neglect it. Otherwise one should also take into account many other neglectible factors most evident of which for me is evaporation.