Water enters a crossflow heat exchanger $($both fluids unmixed$)$ at $16C$ and flows at the rate of $7\mathrm{.}5k\frac{g}{s}$ to cool $10\mathrm{.}0k\frac{g}{s}$ of air from $120C.$ For an overall heat transfer coefficient of $225\frac{W}{m^2}*K$ and an exchanger surface area of $240m^2,$ what is the exit air temperature?

Taking the specific heats of the air and water to be constant at $1\mathrm{.}014$ and $4\mathrm{.}182k\frac{J}{k}g*K,$ respectively, we get