I am planning to repaint the walls and the ceiling of my dining room. The room has the shape of a rectangular box and is 8 m long, 4m wide and 3 m high. I do not need to paint the door and the three windows, the combined surface area of which is 10 m². Paint is sold in 8-litre tins and 1 litre of paint is sufficient for a surface area of 12m².