What is a mathematical equation to predict the final temperature of a mixture of hot and cold water?

The sum of the heat flows from each quantity of water = zero. Or heat lost by Hot water = Heat gained by cold water; Heat lost by hot water is MC(Ti - Tf) Heat gained by cold water is; mC(Tf - ti) M = mass of hot water, m= mass of cold water, Ti = initial tenperature of hot water, ti = initial temperature of cold water, C = specific heat of water, Tf final temp of both waters. mC(Tf - ti) = MC(Ti -Tf)) Tf(m + M) = mti + MTi Tf = (mti + MTi)/(m + M)