A small oven with a surface area of 0.28 m² is located in a room in which the walls and the air are at a temperature of 27°C. The exterior surface of the oven is at 150°C, and the next heat transfer by radiation between the oven’s surface and the surroundings is 586 W. If the average convection heat transfer coefficient between the oven and the surrounding air is 11 W / (m² K) calculate
(a) the net heat transfer between the oven and the surroundings in W, 

(b) the thermal resistance at the surface for radiation and convection, respectively, in K/W, and 

(c) the combined heat transfer coefficient in W/ (m² K).