$30$Kg Iron and $40$ Kg Copper at $80$ oC are dropped into a $15$oC Lake. Please calculate the

entropy change of Iron, Copper, Lake and the total entropy change. $($Ciron $=0\mathrm{.}45$ kJ$/$kg oC$,$ Ccopper

$=0\mathrm{.}386$ kJ$/$kg oC$,$ Cwater $=4\mathrm{.}22$ kJ$/$kg oC$).\backslash$