Hey there!!
Area of a rectangle = Length * breadth.
Length = l
Breadth = x + 4
Area = x² - 16
Identity = a²-b²=(a+b)(a-b)
... x² - 16 = l(x+4)
... l = x²-16 / x+4
... l = ( x - 4 ) ( x + 4 ) / ( x + 4 )
... l = x-4
Hence, the length is 'x-4'
Hope my answer helps!!
