Temperature of water at different temperature mixed together

[semc]

100g of water at 370K are mixed slowly with 200g of water at 290K. What is the final temperature?

Totally no clue where to start. Do I use the specific heat capacity of water? But what is the heat energy?

 

[Stonebridge]

Yes you use specific heat capacity.
The heat lost by the warm water is equal to the heat gained by the cool water.
The clue is that at the end they are both at the same temperature.
Write down the formula for heat gained by the cool water, then equate it to the heat lost by the hot water.

 

[granpa]

temperature is energy / degree of freedom

therefore temperature is proportional to energy