Answer: Most likely, the value of w is 5 units.
Step-by-step explanation: P = 2L + 2w
If the perimeter is 28, the side lengths must be less than 14, otherwise there is no width, just two lines on top of one another.
If the width is 7, then all four sides would be 7 units, and that would create a square-- which is a type of rectangle-- but probably not what this question is about.
A width of 5 units makes sense, 2w would be 10, leaving 28-10 = 18 to be divided by 2 for lengths of 9
The rectangle would have a width of 5 units and a length of 9 units.