A wall $0\mathrm{.}5$ m thick has a position$-$dependent temperature distribution described by the following equation: $()=++$ where T is the temperature in degrees celsius, and x is the distance from the hot surface in meters. Given that $=250,=150/,$ and $=25/,$ and the wall has a thermal conductivity $=2/,$ determine the heat flux at the hot surface $($at x $=0)$ and at the cold surface $($at x $=0\mathrm{.}5$ m$).$