Question

If 400 bricks measuring 81" by 31" are required to build a wall 42 ft. high, how long is the wall? feet.

Answer 1

let b bricks:

b= 400, let  H height and l length

Area = 81*31 or 6.75*2.58 = 17.44 ft²

b(17.44ft²)=Hl

400(17.44 ft²) =42 l

l= 6975/42 = 166.07 

so the length of the wall is 166 ft approximately as a whole number