The length of a rectangle is 4 more than the width the area of the rectangle is 21m squared what is the width

Let, width = x
Length = x + 4

It is given that, (x+4)(x) = 21
x² + 4x = 21
x² + 4x - 21 = 0
x² - 3x + 7x - 21 = 0
x(x - 3) 7(x - 3) = 0
(x+7)(x-3) =  0
x = -7 or 3

Width (Distance) can't be in negative form, so -7 is rejected.

In short, Your Answer would be 3 meter.

Hope this helps!