since the perimeter is 60 and one side of it is 20 then you multiply 20 by 2, 40, to get both sides. Then you subtract 40 from 60 leaving the other two sides as 20, meaning that if you divide 20 by 2 you can find that the width of the dance floor is 10 meters long.
Hey, I can answer in the comments but you need to have the boxes down in the picture if you can tell me the multiple degrees it has in the boxes then I can help thx :)
