Please answer this, show your solutions in paper.I will give you a very good feedback. Thank you!In paper please :(

7. A box with a total surface area of 1.2 m and a wall thickness of 4 cm is made of an insulating material. A 10 watt electric heater inside the box maintains the inside temperature at a steady 15 C above the outside temperature. Find the thermal conductivity of the insulating material. 8. A room has a pine ceiling [ k = 0.12 W/(m-Co)] that measures 3.0 m x 4.0 m x 2.0 cm. On a cold day, the temperature inside the room is 20C, and the temperature in the attic above is 8C. If 6.0 cm of glass wool insulation [ k = 0.042 W/(m-Co) were put in above the ceiling, how much energy would be saved in one hour