NO!

Perimeter is the sum of the side lengths of a polygon, and it is not the area.

A rectangle has 4 sides: 2 sides considered as width and 2 sides considered as lengths.

You can then conclude that the perimeter is

The problem also mentions that the width is one inch less than length. From this, you can conclude that:

Given P, solve for l, and then find w using the given relation.