Hot chemical products $($Cph $=2\mathrm{.}5$ kJ$/$kg K$)$ at $600$o

C and at a flow rate of $30$

kg$/$s are used to heat cold chemical products $($Cp $=4\mathrm{.}2$ kJ$/$kg K$)$ at $200$o

C and

at a flow rate $20$ kg$/$s in a parallel flow heat exchanger. The total heat transfer is

$50$ m$2$ and the overall heat transfer coefficient may be taken as $1500$ W$/$m$2$

K$.$

calculate the outlet temperatures of the hot and cold chemical products.