If a row of plaques cover 120 square feet of space along a wall, if they are 3 feet tall what length do they cover

120 divide it by 3 to get your length.

So, it covers 40 ft of the wall

No a triangle cannot be formed because when you add the two smallest number together (which would be 11) the have to be bigger than the number it is "against" ( which would be 12)

Ican't do any of the other stuff, but i can get you started. the answer, i believe, is $2.50.