The area of a rectangular wall of a barn is 36 square feet. Its length is 6 feet longer than twice its width. Find the length and width of the wall of the barn.

The area of a rectangle is A = length x width

You would therefore get 36 = length x width

Then, since length is 6 feet longer than twice its width,

you would get length = 2 (width) + 6

You would therefore end up with 36 = (2w + 6) x w

solving for width you find it to be 3 feet

Plugging that back in to the area formula, you get 12 feet to be the length.