The area of a rectangular wall of a barn is 168 square feet. its length is 10 feet longer than twice its width. find the length and width of the wall of the barn.

So area is 168 sq ft

That means that length * width = 168 sq ft
Since length  = 10 + 2 w

we get (10+2w)(w)  = 168

Multiply it out and you get 2w^2 + 10w - 168 = 0

This is a quadratic equation. You can use the formula here, but i'll just tell you the answer

w = -12,  or 7
since it can't equal -12 (ever heard of a barn with a length of -12?), you figure out the answer is 7.

If the width is 7, then the length is 10+2(7) = 24.

Have a nice day!