Answer:
Length = 17 feet, Width = 5 feet
Step-by-step explanation:
Given:
The area of a rectangular wall of a barn is 85 square feet.
Its length is 12 feet longer than the width.
Question asked:
Find the length and width of the wall of the barn.
Solution:
Let width of a rectangular wall of a barn = 
<u>As length is 12 feet longer than the width.</u>
Length of a rectangular wall of a barn = 
As we know:


Subtracting both sides by 85

As width can never be in negative, hence width of a rectangular wall of a barn =
= 5 feet
Length of a rectangular wall of a barn = 
Therefore, length and width of the wall of the barn is 17 feet and 5 feet respectively.