A restaurant hall is 20 metres long, 15 metres wide and 5 metres high. Its interior has to be covered with wallpaper. What will be the total expenditure if it costs $60 per square metre of wallpaper?

Answer 1

Assuming you want only the walls covered, you have two pairs of walls, with sizes 20x5 and 15x5.
So, add up the areas to get the m^2, and multiply by the cost per m^2.