The area of a rectangular wall of a barn is 220 square feet. its length is 12 feet longer than the width. find the length and width of the wall of the barn.

Width - x
Length - (x+12)
Area - x(x+12)
x(x+12)=220
x²+12x-220=0     -220 =22*(-10), 12=22-10
(x+22)(x-10)=0
x=-22, x=10

For width we can use only positive number,
so, width is 10 feet.
Length is 10+12=22 feet.