A 669 g sample of water at 83 degrees celsius is mixed with 486 g of water at 23 degrees celsius. What is the final temperature of the mixture? Assume no heat loss to the surroundings.

heat lost by the hot water = heat gained by the cold water

C*669*(83 - T) = C*486*(T - 23)

The specific heat C cancels out.

83-T = 0.726*(T-23)

Solve for equilibrium T