Question 1102558
The area of a rectangular wall of a barn is 126 feet.Its length is 4 feet longer than twice its width.  Find the length and width of the wall of the barn
===================================

126 ft is not a valid representation of area.  126 square feet (sq ft  or  ft^2)  maybe.

Area = Length * Width
126 sq ft = (2W+4)(W)

2W^2 + 4W - 126 = 0
  W^2 + 2W - 63 = 0
    (W-7)(W+9) = 0 
 
W = 7  or W = -9   (discard -9 as Width must be > 0)

W = 7  —>  L = 2(7)+4 = 18 
===
Ans:  Width is 7ft, Length is 18ft
===
Check (always a good idea, especially for me):   7ft*18ft = 126ft^2  (ok)
Also,   18 = 2*7 + 4 = 14+4  (ok)