A thin plate heater is attached to the higher surface of 8 mm thickness aluminum horizontal plate which has thermal conductivity of 235 W/m.K., this surface and the other lower surface of aluminum plate are exposed to air stream of temperature 25 C and convection coefficient 100 W/m2.K. for both surfaces. If the heater dissipates 10 kW/m² under normal conditions, what is the temperature of the lower plate surface?